Who Has Been Avoiding, or Getting Burnt by, Multi-Run Home Runs?

What follows is largely about home runs. In short, I was curious to know what percentage of home runs were multi-run home runs and in turn what percentage were of the solo variety. From there, I wished to determine whether pitchers appeared to have any discernible ability to limit their home runs allowed to empty base situations more often than not. Posed as a question: is allowing disproportionate numbers of solo home runs a skill? And regardless of that, who has been giving up those disproportionately high or low percentages of solo home runs?

First, the solo/multi-run breakdown. Based on data from the last two full seasons, 2018 and 2019, the majority of home runs are solo shots. In 2018, of 5,585 total home runs, 3,316 came with no men on base, per Baseball Savant data. That translated to 59.37%. In 2019, 3,965 of 6,776 home runs came with no men on base, or 58.52% overall. So, in baseball’s presently home run-reliant environment, a bit under 60% of home runs result in just a single run.

Giving up disproportionately high or low numbers of solo home runs won’t distort a pitcher’s reputation like it might have in previous decades. Pitchers have metrics like FIP, xFIP, and SIERA to thank (or curse) for that. Take FIP, which was created by Tom Tango and is agnostic to runs allowed; FIP cares solely about the number of fielding-independent events for any given pitcher. FIP cares not whether runners were on, the home run came to lead off an inning, or that it occurred with two outs: the fact that it happened says enough.

So are some pitchers capable of lessening the damage (by that I mean earned runs) they incur via the home run ball by buckling down with runners on base? Logically, if they were, it would probably be advisable for pitchers to simply “buckle down” the whole game if they were so capable. Additionally, those who have read “The Book” by Andrew Dolphin, Mitchel Lichtman, and the aforementioned Tom Tango know that pitchers experience differing levels of success pitching out of the windup versus the stretch. This fact is an obvious confounding factor for any sort of rigorous evaluation.

Leaving that dilemma unaddressed entirely, I employ the simplistic tactic of juxtaposing season-over-season solo home run percentages to visualize any potential relationship for home run-prone pitchers.

Even after engaging in some shameless cherry picking across increasingly small samples, two fairly obvious takeaways arise given the three scatterplots above. First, there is no evident relationship between pitcher solo home run percentages across these seasons. Second, it takes an incredibly small sample of particularly home run-prone pitchers to generate even a weak positive correlation between solo home run percentages.

In absence of further investigation, it seems pretty safe to say limiting home runs to solo situations does not appear repeatable and isn’t therefore a real talent or skill.

Still, among the original group of 126 pitchers, a handful seem to have interestingly low, or high, percentages of solo home runs allowed. Given this, I’ve included a couple charts. The first covers those pitchers who gave up a relatively low percentage of solo home runs. The second covers those who gave up a relatively high percentage of solo home runs. Theoretically, those with the low solo home runs percentage would be more likely to have a positive ERA FIP differential than those with a low solo home run percentage.

Steven Brault, Matt Harvey, Rich Hill, Felix Pena, Homer Bailey, and Jason Vargas have all had the bad luck of giving up >50% of their home runs while runners were on base across 2018 and 2019. While this doesn’t impact their FIP figures, their ERAs surely didn’t benefit.

Blaine Hardy holds the unenviable distinction of having given up double-digit home runs primarily as a reliever in 2018/19. That said, exactly 80% of those home runs allowed only accounted for single runs. Adam Plutko and Justin Verlander, though, alone each gave up 20+ home runs in both seasons with nearly identical 75%+ without runners on base. Of those, I chose to check out the anecdotal history of Verlander for two reasons. First, his longer track record and, second, his commentary in the past on MLB’s baseball and how that baseball has corresponded to a spike in longballs.

Baseball Savant’s search tool runs back to 2008, so the first 64 starts of Verlander’s career are not included in the chart below. Still, even with the slightly truncated view, it is clear that Verlander has been especially prone to allowing home runs at the least damaging moments (from an earned runs perspective, at least). While giving up home runs is surely no fun, at the very least he has avoided giving up as many runs as a league-average situation would suggest.

In particular, since Verlander seemingly remade and reestablished himself in 2016, he has been able to sequester his home runs allowed to bases empty scenarios. It’s not a skill, and the title of this post is therefore somewhat of a misnomer, but his track record is quite clear nonetheless.