Sixto Sanchez, Christian Yelich, and Retroactively Thinking About Probability

Last night, headline came across that Phillies top prospect Sixto Sanchez had a setback and would miss the Arizona Fall League. This largely sent everyone into a panic. Sanchez is a divisive player in Phillies fans circles. To some he is untouchable, the kind of elite prospect that teams shouldn’t trade. To others he is the key to acquiring what they want and the missed opportunity of what could have been acquired. The Phillies clearly fall into the first camp, which is why he is still with the team. That doesn’t mean the other side doesn’t have a point, but there is of course more here than some sort of binary black and white.

But, before getting into the complexity let’s get to where we are now a day later, when it comes to Sixto Sanchez. He got off to a slow start this year due to illness, and after getting his feet wet, he dominated for a time period, before his elbow started hurting. The Phillies called it minor, but he didn’t pitch after June 3. The Phillies then announced he would be pitching in the Arizona Fall League and began stretching him back out. On September 22, he pitched in a live game for the first time since June, and those at the game had him sitting 94-99, touching 100. That is maybe 1-2 mph below peak, but not out of the range of a normal appearance. At some point after that, Sanchez mentioned soreness in his collarbone and the Phillies decided to shut him down.

To this point, Sanchez has no history of arm injuries. He does have a long history of the Phillies babying, mostly because he didn’t turn 20 until July 29, and they value him highly. There are rumors that Sanchez is taller than the likely 5’10”-5’11” he was last year and that he might be a bit larger around the stomach. Height wise, there isn’t a ton of evidence that small pitchers are more injury prone, and Sanchez throws the ball fairly easily from an athletic and repeatable delivery. In other words, there are not a ton of elevated injury risks outside of his velocity and him being a pitcher.

That brings us to the confusion that is Sixto Sanchez the baseball asset (I say asset because this next segment isn’t really about Sixto Sanchez the person and more the concept that is Sixto Sanchez). With any prospect, a team has two choices, hold or trade. A team can hold to future trade, but each moment is a choice between the two. In each of those moments a player has a value. In this case that value is some sort of probability of their outcome, but it is not their outcome. Right now, Sixto Sanchez is rated by MLB.com as the #21 prospect in baseball. It is almost certain the Sanchez will not be the 21st best player of the group. If he hits his ceiling, Sanchez will be a Cy Young candidate and one of the best pitchers in baseball, with a fall back that is probably the best relief pitcher in baseball (under a scenario where he can’t handle that level of workload). There is probably some middle ground where Sanchez just doesn’t find the consistency on any of his pitches and is an inconsistent mid rotation arm, but more likely the downside is that you get nothing. Thus the probability here is how certain you are that he is to achieve the top outcome and not the bottom one.

For the most part when you trade a prospect you are trading for a major league piece. That player is often at their prime, with some amount of financial commitment, and the calculus of probability for many teams becomes, how much monetary value do they have. There is also a separate calculus of how much does that player actually help me achieve tangible outcomes (which is a topic for a totally different discussion and why Manny Machado is not in the headline). However, for all of this, let’s throw money aside. That is because I want to talk about a player who is coming into their peak, and the player the Phillies have long coveted and who turned into the likely NL MVP, and that player is Christian Yelich.

We probably won’t know for sure, but if the Phillies had included Sixto Sanchez in a deal, then Yelich probably is with the Phillies this year. Instead he went to Milwaukee and hit .326/.402/.598. If the Phillies knew that he would do that, they 100% put Sanchez in the deal and have Yelich in red pinstripes, no one is arguing that. There is only one small problem, in his first 5 years, Yelich hit .290/.369/.432 in 643 games. He played in a park that killed power, he was only 25, and he had a season slugging .483 back in 2016. There is reason to think that his ceiling was more towards the line he put up in 2016, maybe with some more growth for age and ballpark change. Baseball Prospectus’ PECOTA system put out a 90 percentile prediction of Yelich at .309/.392/.485, likely with Miami as his home park. That is a very very good season, and possibly a bit conservative on the outcomes. But what did everyone miss on? The outlier.

In 2018, Yelich had a 35.0% HR/FB rate. In the past 5 seasons, the only two players to be in that ranger were Aaron Judge (35.6%) and Giancarlo Stanton (34.3%) last season at the height of the juiced ball era. Yelich’s career high was 23.6% entering the year, and is still at 20.3% for his career with this outburst. If you predicted Yelich would do this you would be crazy. There is a chance that in Philly Yelich hits a very Cesar Hernandez level .282/.369/.439. If he does, the Phillies still probably miss the playoffs. I don’t think they complain about their future, but they will have given up their top prospects to finish behind the Braves just the same. That is the context of the event, that hold or trade event, not the MVP season.

This brings us back to Sixto Sanchez and how the Phillies feel, because they are going to make that decision again, hold or trade. In this, other teams are going to try and value Sanchez as the 20th best prospect in baseball or below it. If you are the Phillies and you don’t believe in the health you probably trade him, but if you do believe in the health, you cannot treat him as the 20th best prospect in baseball, doing so is selling low. When it does come to that moment, time gets frozen, because we don’t know the outcome and we don’t get to let them factor in when they do happen, because each moment is a different evaluation and the right decision is not always the correct one.