What would a Herrera-Vierling platoon look like statistically?

The Phillies are reportedly bringing back Odubel Herrera to use as the left-handed side (the “long” side) of a platoon in Center Field.

When they bought out Herrera’s $12.5M option for 2022 for $1.0M last Fall, we knew there was at least a theoretical chance that they could then re-sign him for less than $11.5M and thereby save money relative to the option. His 2022 contract is for $1.75M guaranteed, and up to $2.5M with incentives,

The right-handed side of the CF platoon would likely be Matt Vierling, at least as of now. Vierling did well in a very short stint in the majors last season: 77 PAs, .324/.364/.479.

Platooning: the lay of the land

Platooning is complicated by the fact that there are many more right-handed than left-handed pitchers. In the National League last season, it was essentially a 72-28 split:

• 72.4% of plate appearances were against RHPs
• 27.6% of PAs were against LHPs

The relative abundance of RHPs make it easier to limit how often lefty hitters face left-handed pitchers: instead of facing RHPs only 72.4% of the time, left-handed hitters in platoons often have the platoon advantage in up to 90% of their PAs, or even more.

For right-handed hitters, it’s tougher to limit them to facing only lefties, since there are fewer LHPs, but with diligent managing the ratio of their PAs with a platoon advantage can be increased from 27.6% up to 50%, though usually not much more than that.

The Phillies’ CF Platoon

For our purposes here we’ll assume Herrera will face RHPs in 90% of his PAs, and Vierling faces LHPs in 50% of his.

For Herrera’s stats, we’ll use the rate stats in his 2021 splits. The various projection systems predict that, overall, he’ll be at or somewhat above this 2021 production:

• vs. RHPs (339 PA): .264/.313/.431 (.744 OPS)
• vs. LHPs (153 PA): .252/.305/.381 (.686 OPS)

For Vierling, it’s trickier because a) his 2021 major league stats were such a small sample, and b) he had an unsustainably high 33.3% HR/FB rate vs. RHPs, inflating his slugging numbers:

• vs. RHPs (34 PA): .300/.353/.567 (.920 OPS)
• vs. LHPs (43 PA): .342/.372/.415 (.787 OPS)

We can instead use his overall 2021 splits, which combined time in AA (102 PA), AAA (236), and MLB (77), for a total of 415 PAs. Over that larger sample, he showed a more typical split for a right-handed hitter:

• vs. RHPs (283 PA): .263/.346/.436 (.783 OPS)
• vs. LHPs (132 PA): .331/.386/.479 (.866 OPS)

For 2022, we’ll assume the slash lines below for Vierling, which will hopefully turn out to be conservative:

• vs. RHPs: .243/.303/401 (.704 OPS)
• vs. LHPs: .303/.335/.418 (.753 OPS)

2022 Projection

With Herrera getting (roughly) 90% of his PAs vs. righties, and Vierling about half of his against either side, and assuming for argument’s sake that nobody else plays any innings in CF, we get the following full season stats:

In 2021 a .738 OPS would have ranked 12th out of the 30 teams for CF production. In terms of overall value, the 12th ranked team produced 3.2 fWAR from their center fielders, and the 13th team 2.8. It’s fair to say a .738 OPS would result in roughly 2.5-3.0 WAR, depending on how good the fielding and baserunning are.

That’s ok, not great, but let’s compare it to what the Phillies got from their center fielders in 2021:

• .230/.298/.363 (.660 OPS, 28th in MLB)
• 76 wRC+ (27th in MLB)
• 0.4 fWAR (26th in MLB)

The start of 2021 was so bad that even Herrera’s decent, if inconsistent, production barely dragged the CF stats out of the very bottom of MLB for the season as a whole. If this platoon can provide something close to the middling production in the estimate above, it would be a notable improvement from that very low bar.

Summary

Whether one looks at a blog like this, or Twitter, or listens to sports talk, it’s abundantly clear that a significant portion of the fanbase has already seen more than enough of Odubel and would like to move to something — anything — else.

What’s more, from a baseball perspective he doesn’t provide the improvement that fans are looking for. His occasional gaffes are infuriating, and although they’re largely baked into his hitting, fielding, and baserunning stats, the bottom line remains that those stats are somewhat below average.

However it should be said that if he can provide even the minimal production he did last year, pairing him with Vierling should give the Phillies middle-of-the pack production from their center fielders. That’s not much, but it would be a couple-win improvement over the 2021 version.

So as uninspiring as this plan may be, it’s most likely a clear improvement over 2021. Depending on how Vierling performs, it also has a chance for much more that.

Now, we’d love to say we’ll come back in seven months and see how the results compare to the above projection, but as we know things typically don’t go as planned. One or both of these players could get hurt, or someone could take a step forward and get more playing time. It would be great if that was Vierling, and he shows that last year’s brief audition wasn’t a fluke.