Jeremy Mand: WILD THINGS: Why the Mets Bullpen’s BB% could determine the season.

The 2021 Mets possess perhaps, some will argue, the most talented bullpen in all of major league baseball. 

By talent, I mean, they collectively have the best “stuff,” as many commentators or former ballplayers, scouts and coaches put it. But distilled down to one variable, all we mean is they throw the hardest.  

Can you name a team in 2021 with more high octane arms than the New York Mets have when healthy? Edwin Diaz, Jeurys Familia, Trevor May, and Miguel Castro - as well as Dellin Betances and Seth Lugo (when healthy), might have the most potent arsenal of four seamers we have ever seen over the course of a full season in Queens.

Not to mention other high velo arms that are expected to contribute like Drew Smith, Robert Gsellman, Ryley Gilliam, Arodys Vizcaino, Thomas Szapucki, and Mr. Wild Thing himself, Sam McWilliams, who earned a pricey $800,000 contract major league contract despite never throwing a pitch in the major leagues, probably only because he throws 95+.

So, are the Mets stable of hard throwers going to mean less indigestion for our fans in the late innings?

Probably not.

While fans, scouts and front offices may be enamored with hard throwers, the data shows that is not the right metric to look at when it comes to production. 

In fact, in the aggregate, there is hardly any correlation between velocity and success. The R² , a statistical metric used in linear regression analysis which measures the relation between two variables, show that ERA for all qualified relievers between 2018 and 2020 is nearly zero in relation to velocity. Meaning there is no correlation between velocity and success.

In 2020, the Mets pen was the 7^th hardest throwing in baseball, and would have been higher if not for injuries, but they were 18^th in ERA, and that was largely driven by the 2^nd worst in the league BB/9 rate of 5.06. In fact, it is the BB% that is significantly more indicative of success, with an R² of 0.09 or 9%. 

                              

While the Mets have quite a deep bench of throwers, and strikeout artists, the success of their bullpen is going to largely depend on their ability to throw strikes. 

As an aside, speaking of strikeouts, and this is perhaps why fans and scouts are so enamored with velocity, there is a very strong correlation between velocity and strikeouts, as seen below.

                             

The logic is I think, if a batter strikes out, they aren’t putting the ball in play, and thus there is less chance to get on base via error, or luck, and thus they will not score. This is true. But what is the cost of buying all these strikeouts? 

The R² between strikeouts and bb’s is 7%. Meaning gaining more strikeouts is coming at the cost of more walks. 

And, as I said, fewer BBs means lower ERAs, to the tune of 9%. So the logic really doesn’t work when it comes to run prevention. Maybe the logic is that with more strikeouts you can carry poorer defensive players, and it's made up for with better offense?

Now of course, the best pitchers will have high K rates, low BB rates, and thus low ERAs, but not every reliever in baseball is Liam Hendriks. 

For a team and a sport that has evolved and promoted evaluating talent based largely on advanced statistical techniques, it’s quite interesting that such an insignificant variable, fastball velocity, has made a lot of undeserving players a lot of money, destroyed careers, and continued or discontinued careers, more so than ERA, the actual metric which measures runs allowed. 

Former Met reliever Chasen Bradford  and I have discussed the inherent stupidity of judging talent on velocity alone. 

I support his cause and his case, not because I'm trying to do him a solid, but because he is right-- here is a guy with a 1.28 career WHIP (which is definitely correlated to ERA) and he can’t get a job, because he throws 90-92 and has only a 20% K rate. 

At the same time, a reliever like Jeurys Familia, who tantalizes us with his velocity and movement but has shown a propensity to walk the ballpark is making $11 million per year. This is not to single out Familia, he has been great when he throws strikes, but he just doesn’t often enough, at least in recent years. I guess they call it the major leagues “the show” for a reason, because an inconsistent fire baller is more exciting than a boring control pitcher right?

So, back to the Mets real quick, when assessing whether or not he Mets pen will be great in 2021, you need to stop and ask only one question – will the 2021 Mets pen throw strikes, if the answer is yes, then they probably will be pretty good; if not, our stomachs might be churning more and more.