Name: Gunner Mayer
Position: RHP
Born: July 27, 2000
Country: United States
Bats/Throws: R/R
Height/Weight: 6’6″ 190lbs
How Acquired: Drafted in the 5th Round of the 2019 Draft by the Phillies
Signed: June 11, 2019
Bonus: $600,000
Options Remaining: 3
Rule 5 Eligible: 2023
MiLB Free Agency: 2025
Stats
Prospect Rankings
Mayer moved full time to the bullpen in 2024 and at times looked like he might break out, but his control continued to hold him back. He is 93 to 97 out of the bullpen with a cutter and occasional changeup.
Role: #5/#6 Starter
Risk: High – Mayer probably has a bit more upside, from physical projection, than up and down starting pitcher, but right now his stuff is more fringy. He doesn’t have the fastball or secondary pitches to profile as a reliever.
Summary: Due to his inexperience pitching and age, Mayer was functionally a high school level arm when drafted. Due to the pandemic and injuries he pitched under 90 innings total over his first four pro seasons. His 77.1 innings in 2023 represented a career high, and he ended up pitching in 23 games and spending the full season in the BlueClaws starting rotation (both his relief appearances were “starts” after a rehabbing player on reduced innings). Mayer still has room for a little more velocity, but sat mostly 90-94 in 2023. He throws a trio of secondary pitches, and both the curveball and changeup have shown promise at times, but overall he has lacked consistency. Delivery and command consistency have also been a problem for him, and there were multiple starts where he racked up a bunch of base runners and pitches early and was out of the game quickly. The shine has started to come off of Mayer, and he is going to have to show actual growth next season, and not just the ability to stay on the mound.
2024 Outlook: Mayer pitched the full season at Jersey Shore, so a trip to Reading seems in the works. He will need to start to put up actual results on the mound and not just physical potential.
Role: #4 Starter
Risk: Extreme – Mayer is still a 22 year old pitcher who has yet to get past low-A and has yet to throw a full season of innings. The improvements he made this year do look like they should help him in the long term, he just is further away than you would want.
Summary: The Phillies took Mayer as an 18 year old recent pitching convert out of junior college in 2019. The now 22 year old, tall righty has struggled to stay on the mound and log innings the last two seasons, as an injury cost him most of May and June this season. Statistical success has been fleeting for Mayer as well, as he has struggled to economically work deep into games. If you just looked at fastball velocity, it might look like Mayer is the same pitcher he was in 2021, but if you look at video or pitch tracking data, there are some subtle changes that the Phillies made. Mayer is more over the top with his delivery, and the result has been a straighter and flatter fastball and a more vertical curveball. He also threw his changeup more this season and spent a couple of starts mixing in a slider. Mayer’s fastball still averages right around 92 mph, but he can get up to 96. It is a high spin pitch that plays well up in the zone, but he struggles to locate it consistently. His curveball is a big dropping bender that has been bleeding spin a bit over the years. Mayer’s control issues coupled with strong flyball tendencies have led to high home run rates as well. Overall it was a step forward year for Mayer, but after 4 years in the system, he is still a project and, like many, the missed season has definitely stunted some growth.
2023 Outlook: Now healthy, Mayer should move up to Jersey Shore where it will be important for him to log a full season of innings and show some consistency on the mound. At 22, and many years into his time in the Phillies org, this also is likely the big season to look for him to actually make a jump in stuff and outlook.
Role: #4 Starter
Risk: Extreme – Mayer is still fairly young, but he only has 34.2 innings pitched since being drafted in 2019. He is a slightly better project than when he was drafted, but he is still more projection than actual tools.
Summary: Mayer had just recently moved to the mound when the Phillies took him in the 5th round of the draft in 2019. He still shows arm strength, with his fastball up to 95.9 per Statcast with spin rates over 2400 rpm. He has a changeup and a curveball, but the curveball spin does not match the fastball spin. He missed bats for Clearwater, but also had a hard time consistently throwing strikes. Mayer had an arm injury that caused him to miss a chunk of the season, and the Clearwater COVID shutdown cost him more time. He is still a projectable project, but he has a lot less margin for error and development bumps than he did 2 years ago. If things start to slide, you can see a scenario where the physical project and velocity potential, combined with shortening him in a relief role, could make for an interesting pitcher given his fastball characteristics.
2022 Outlook: Assuming he is back fully healthy, Mayer should be part of whatever form the Jersey Shore rotation takes. This year isn’t make or break, but he does need to start showing larger steps forward.
Gunner Mayer is only 20 despite being a JuCo pick in the 2019 draft. He is a big (6’6”) projectable starting pitcher that had barely pitched when the Phillies took him and only logged 8.1 GCL innings in his draft year. He already has solid velocity, but he is making improvements with very little pitching and might be on the verge of a breakout.
Role: #3 Starter
Risk: Extreme – Part of being bullish on Mayer’s upside is acknowledging how much growth is still needed. He has never completed a year as a starter, only shows a breaking ball, and is missing a changeup.
Summary: It is hard to judge Mayer as he currently is as a baseball player. He is a former infielder who just recently converted to pitching, and was young for a first year JuCo player, so he is still not done physically growing either. He is listed at 6’6” and is fairly skinny. The word projectable gets thrown around a lot, but there are clearly many places for Mayer to add muscle. He already has some arm strength, hitting up to 94 this spring and in the GCL. He has shown feel for a curveball and slider, but will need to develop a changeup. He is far from a finished product, and tall pitchers tend to have struggled syncing up their deliveries. Due to his projectability and athleticism, he is the definition of a high upside pitching project. He will take some time and the Phillies shut him down early after his debut, so a piggyback spot in the Lakewood rotation seems like the logical 2020 path.
2020 Outlook: Given his newness to pitching, the Phillies will likely keep Mayer’s inning total down in 2020. They could let a piggy back system in Lakewood keep the numbers down on it’s own, or they could be more aggressive by either starting him in Extended Spring Training or shutting him down early. Either way it is likely a summer on the Jersey shore for him.
2025 UR
Mayer moved full time to the bullpen in 2024 and at times looked like he might break out, but his control continued to hold him back. He is 93 to 97 out of the bullpen with a cutter and occasional changeup.
2024 #53
Role: #5/#6 Starter
Risk: High – Mayer probably has a bit more upside, from physical projection, than up and down starting pitcher, but right now his stuff is more fringy. He doesn’t have the fastball or secondary pitches to profile as a reliever.
Summary: Due to his inexperience pitching and age, Mayer was functionally a high school level arm when drafted. Due to the pandemic and injuries he pitched under 90 innings total over his first four pro seasons. His 77.1 innings in 2023 represented a career high, and he ended up pitching in 23 games and spending the full season in the BlueClaws starting rotation (both his relief appearances were “starts” after a rehabbing player on reduced innings). Mayer still has room for a little more velocity, but sat mostly 90-94 in 2023. He throws a trio of secondary pitches, and both the curveball and changeup have shown promise at times, but overall he has lacked consistency. Delivery and command consistency have also been a problem for him, and there were multiple starts where he racked up a bunch of base runners and pitches early and was out of the game quickly. The shine has started to come off of Mayer, and he is going to have to show actual growth next season, and not just the ability to stay on the mound.
2024 Outlook: Mayer pitched the full season at Jersey Shore, so a trip to Reading seems in the works. He will need to start to put up actual results on the mound and not just physical potential.
2023 #28
Role: #4 Starter
Risk: Extreme – Mayer is still a 22 year old pitcher who has yet to get past low-A and has yet to throw a full season of innings. The improvements he made this year do look like they should help him in the long term, he just is further away than you would want.
Summary: The Phillies took Mayer as an 18 year old recent pitching convert out of junior college in 2019. The now 22 year old, tall righty has struggled to stay on the mound and log innings the last two seasons, as an injury cost him most of May and June this season. Statistical success has been fleeting for Mayer as well, as he has struggled to economically work deep into games. If you just looked at fastball velocity, it might look like Mayer is the same pitcher he was in 2021, but if you look at video or pitch tracking data, there are some subtle changes that the Phillies made. Mayer is more over the top with his delivery, and the result has been a straighter and flatter fastball and a more vertical curveball. He also threw his changeup more this season and spent a couple of starts mixing in a slider. Mayer’s fastball still averages right around 92 mph, but he can get up to 96. It is a high spin pitch that plays well up in the zone, but he struggles to locate it consistently. His curveball is a big dropping bender that has been bleeding spin a bit over the years. Mayer’s control issues coupled with strong flyball tendencies have led to high home run rates as well. Overall it was a step forward year for Mayer, but after 4 years in the system, he is still a project and, like many, the missed season has definitely stunted some growth.
2023 Outlook: Now healthy, Mayer should move up to Jersey Shore where it will be important for him to log a full season of innings and show some consistency on the mound. At 22, and many years into his time in the Phillies org, this also is likely the big season to look for him to actually make a jump in stuff and outlook.
2022 #37
Role: #4 Starter
Risk: Extreme – Mayer is still fairly young, but he only has 34.2 innings pitched since being drafted in 2019. He is a slightly better project than when he was drafted, but he is still more projection than actual tools.
Summary: Mayer had just recently moved to the mound when the Phillies took him in the 5th round of the draft in 2019. He still shows arm strength, with his fastball up to 95.9 per Statcast with spin rates over 2400 rpm. He has a changeup and a curveball, but the curveball spin does not match the fastball spin. He missed bats for Clearwater, but also had a hard time consistently throwing strikes. Mayer had an arm injury that caused him to miss a chunk of the season, and the Clearwater COVID shutdown cost him more time. He is still a projectable project, but he has a lot less margin for error and development bumps than he did 2 years ago. If things start to slide, you can see a scenario where the physical project and velocity potential, combined with shortening him in a relief role, could make for an interesting pitcher given his fastball characteristics.
2022 Outlook: Assuming he is back fully healthy, Mayer should be part of whatever form the Jersey Shore rotation takes. This year isn’t make or break, but he does need to start showing larger steps forward.
2021 #27
Gunner Mayer is only 20 despite being a JuCo pick in the 2019 draft. He is a big (6’6”) projectable starting pitcher that had barely pitched when the Phillies took him and only logged 8.1 GCL innings in his draft year. He already has solid velocity, but he is making improvements with very little pitching and might be on the verge of a breakout.
2020 #38
Role: #3 Starter
Risk: Extreme – Part of being bullish on Mayer’s upside is acknowledging how much growth is still needed. He has never completed a year as a starter, only shows a breaking ball, and is missing a changeup.
Summary: It is hard to judge Mayer as he currently is as a baseball player. He is a former infielder who just recently converted to pitching, and was young for a first year JuCo player, so he is still not done physically growing either. He is listed at 6’6” and is fairly skinny. The word projectable gets thrown around a lot, but there are clearly many places for Mayer to add muscle. He already has some arm strength, hitting up to 94 this spring and in the GCL. He has shown feel for a curveball and slider, but will need to develop a changeup. He is far from a finished product, and tall pitchers tend to have struggled syncing up their deliveries. Due to his projectability and athleticism, he is the definition of a high upside pitching project. He will take some time and the Phillies shut him down early after his debut, so a piggyback spot in the Lakewood rotation seems like the logical 2020 path.
2020 Outlook: Given his newness to pitching, the Phillies will likely keep Mayer’s inning total down in 2020. They could let a piggy back system in Lakewood keep the numbers down on it’s own, or they could be more aggressive by either starting him in Extended Spring Training or shutting him down early. Either way it is likely a summer on the Jersey shore for him.
Season Reports/Highlights
Mayer had just moved to the mound when the Phillies took him in the 5th round of the 2019 draft. He is still a work in progress and an injury slowed him up some. His fastball sits in the low 90s and will touch up to 96. He throws a changeup and curveball with his changeup being his best weapon. He is still a skinny 6’6” and is very much still a project in terms of feel for pitching and physical projection.
2021 Midseason #32
Mayer had just moved to the mound when the Phillies took him in the 5th round of the 2019 draft. He is still a work in progress and an injury slowed him up some. His fastball sits in the low 90s and will touch up to 96. He throws a changeup and curveball with his changeup being his best weapon. He is still a skinny 6’6” and is very much still a project in terms of feel for pitching and physical projection.