I'm curious if there is a way to evaluate the potential effect a particular baserunner has on the pitcher-batter exchange. Would having Billy Hamilton on the basepaths noticeably make Joey Votto hit better (or if easier to search, make the pitcher worse)? Can you use B-R to compare certain players when they're on base to figure out the positive or negative change in batters' success as compared to the general change of batters' success with John Everyman on base.
I'm guessing with Hamilton on base, Votto will maybe see more fastballs than if Todd Frazier is on, so maybe he'd hit better? Or perhaps the pitcher is just so rattled that he gets wilder than usual. Mostly, I'm just curious to see the results, and hoping there's a player who, just by being on the bases, makes his teammates hit way worse.
And by another listener, Matthew Tobin:
Is there any statistical evidence that Votto enjoys more fastballs in the zone when Hamilton is on base? That he is enjoying an advantage when when Billy Hamilton is on base? Are there any notable examples in baseball when exceptional speed on the bases provides a significant boost with him on bases vs. when that hitter is not on base?
Those questions made me curious, so I decided to take a look. And so it came to pass that as part of BP's partnership with Fox Sports, I have an article up at the Fox Sports MLB page today on the very same subject. Here's an excerpt:
Hamilton’s performance so far falls well within the range of possible outcomes that Baseball Prospectus’ projection system, PECOTA, forecast for him this season. Hamilton’s weighted-mean PECOTA projection called for him to have a .305 on-base percentage and a .242 True Average, near matches for his actual .299 and .241 marks to date. Despite that dismal projected performance at the plate, though, the system expected Hamilton to be worth over three Wins Above Replacement Player, thanks to his plus defense in center and projected 73 steals.
Real-life Hamilton has been an above-average center fielder, and he was on pace for right around 73 steals before being sidelined earlier this month by a nasty case of sprained knuckles (though he’s been caught in almost 30 percent of his attempts, which PECOTA didn’t predict). Hamilton’s ancillary skills have helped him make up for some of his offensive struggles. In fact, they may have helped more than we know. Is it possible that Hamilton has a heretofore hidden skill that no projection system or advanced statistic can capture?
To get some answers, check out the full article—and stay tuned for future exclusive weekly columns by Baseball Prospectus for Fox.