Uncertainty, Mookie Betts, and Javier Baez

A number of people who are actually good at math have asked before why we don’t present measures of uncertainty, like error bars, when talking about WAR or projections. I’m not in charge of those things, myself, so I can’t give you the official answer, but, they’re difficult numbers to calculate, if they’re possible at all, and many people wouldn’t know how to understand them, and it’s unclear how much those measures would add to the picture anyway. Sometimes you’ll see projections presented in percentiles, like PECOTA, but generally speaking the percentiles can include almost any and all outcomes, so that doesn’t help much. There’s interest in seeing uncertainty, quantitated. It’s challenging, to do it in a meaningful way.

But I want to try something, again with your help. Last week, I ran a bunch of polls, and a few days ago I analyzed the information generated. Here I’d like to take a similar approach. Now, the post was inspired by the transcript of Dave’s Wednesday chat:

Comment From Curtis
Of all the prospects yet to debut in MLB, who has the highest bust probability in your eyes? Best chance to succeed?
Dave Cameron: Baez seems to have a very high chance of being nothing. Mookie Betts will be a solid player unless he dies.

Let’s think about Javier Baez and Mookie Betts. Let’s see what we can do to effectively crowdsource their uncertainties.

Now, this leans on an assumption, that Dave is at least in the vicinity of being right. Though it isn’t exactly what he said, I think Dave would agree with this statement: Mookie Betts is more predictable than Javier Baez. Dave also agrees with this statement: Mookie Betts is a safer prospect than Javier Baez. Whether they’re the most and least, I don’t know, but I think it’s fair to say that Betts and Baez occupy opposite extremes. They’re extraordinarily different sorts of prospects. Betts is seemingly all about having a high floor. Baez is pure boom or bust. It’s easy to see the ceiling, and it’s exactly as easy to see him flaming out.

You don’t want to get too carried away, of course. You don’t want to get too committed to labels or preconceived notions. There’s risk with every player, and certainly with every young player. Betts isn’t a lock. We can talk about him like he is, but, he isn’t. I’ll never forget being told that Dustin Ackley was ultra-safe. One of those guys who falls out of bed and hits .300. And indeed, Ackley had a very impressive big-league debut. After a couple thousand trips to the plate, he’s in possession of a 92 wRC+. Safe players fail.

And you don’t want to forget how much raw ability Baez has. You don’t want to focus too much on the negatives. Those negatives come with unquestionable 80 bat speed. Baez has an elite-level skill. Sure, he’s thought of as risky, but, George Springer had trouble making contact everywhere. Or, if you prefer: lots of people are on board the Kris Bryant bandwagon. Awesome prospect, Kris Bryant. He’s supposed to have a high floor. Bryant’s also struck out a lot. Last year in Triple-A, Baez made 63% contact. On the same team, Bryant made 65% contact. The swings are different, and the discipline is different, but, contact is contact. Baez makes good contact when he makes contact.

If you want to break it down way too simply, Betts and Baez have both proven they can look good in the majors:



And also, Betts and Baez have both proven they can look bad in the majors:



Let’s take this back to the purpose. Betts and Baez have certain probabilities of big-league success. They also have certain probabilities of big-league failure, or at least big-league disappointment. We don’t know exactly what those probabilities are, but I think many people have some sort of idea how they compare. While fighting the urge to exaggerate, it seems the consensus is that Baez has the higher bust potential. Betts has the narrower band of potential outcomes. Baez is the more uncertain player, and though we understand that as an idea, the point here is to try to find a number.

Just how might the uncertainties compare to one another? I want to try taking the polling approach. The best any of us can do is guess, since we can’t readily analyze a million different futures, but you guys make a crowd and the crowd knows a lot. So this is an attempt to crowdsource uncertainty by asking for 2015 offensive projections. We’re using Mookie Betts and Javier Baez because I’m not sure you could find two more different upper-level position-player prospects, in terms of how they profile. Because this just focuses on two players, there’s not much we can do with the information, but it might be a starting point. How safe is arguably the safest prospect? How unpredictable is arguably the most unpredictable prospect?

These should be self-explanatory:

This considers just the season ahead, and not entire careers, but I think it should work fine as a proxy for uncertainty; people who like or don’t like Betts will like or not like him for 2015. The same could be said for Baez. I doubt anyone expects Baez to suck in 2015, and then be great. I similarly doubt the opposite of that.

If enough votes come in, I’d like to analyze the data as soon as later today. Or maybe no one will vote, or maybe Max Scherzer will sign with the Phillies in six minutes. But I’ll come back to this at some point, provided there’s even anything to discuss. Thank you for your gracious participation, or even for your reluctant participation. I don’t care why you participate.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

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Stringer Bell
Stringer Bell

Baez- 73 wRC+
Betts- 136 wRC+

I am extremely high on Mookie.


But what if he’s nothing but 40 degree days?


Ain’t nobody got nothing to say about a 40-degree day.

Banking on Baez to be my 60-degree day.


Isn’t it a little early in the day to be that high?

Jason Bourne
Jason Bourne

It’s 11 o’clock somewhere.


It’s 4:20 somewhere