Apropos largely of nothing — except his notable performance, I suppose, in this past Saturday’s Arizona Fall League Rising Stars Game — I’ve dedicated considerable attention to Reds (now) outfield prospect Billy Hamilton in these electronic pages over the last 48 hours.
Hamilton, because he has a tool (in this case, speed) considered by many to be generational, has produced excitement among prospect analysts. In some cases, that excitement is analogous with optimism about Hamilton’s future as a major leaguer; in other cases, it’s more of an aesthetic judgment than any sort of projection about Hamilton’s career.
I wanted, briefly, to speak to the first point — and, specifically, to establish some sort of framework (however rough) for what speed is actually worth in terms of runs and wins.
I’m mostly certain when I suggest that speed produces runs in three main ways: by means of defensive range, baserunning (both via the stolen base and other manner of advancement), and infield hits/drag bunts. In the case of the first two elements (range and baserunning), speed alone isn’t even responsible for the entirety of the skill. There are excellent defenders, for example, whose range is due not only to footspeed but also to making good reads on, and taking straight paths to, batted balls. Likewise, there are players with merely average speed who, nevertheless, are above-average baserunners due to excellent decision-making. For the sake of this post, however, both elements will be considered purely as expressions of footspeed.
The question of infield hits and drag bunts is problematic in a different way, in that both components inform a player’s batting numbers directly. Because it’s “baked in” to a player’s offensive slash lines, we’ll ignore it for the sake of this post. Our concern is more with the first two, less immediately visible, metrics.
Now, with regard to those less visible metrics: to determine something like a ceiling in terms of runs/wins both of defensive range and baserunning, I considered what league leaders in both categories generally produce.
For defensive value, I looked at UZR-plus-positional adjustment for all outfielders — to account not only for center fielders, but other defensively talented players, as well (like Brett Gardner or Desmond Jennings), who merely happen to play a corner-outfield position. I omitted infielders, as their hands and throwing ability factor much more significantly into their run-prevention skills. The inclusion of arm-related run prevention isn’t particularly problematic, it seems: for most every outfielder who’s not Alex Gordon, really, range is the primary informant of run prevention. For baserunning, I looked at the baserunning metric (for outfielders only, for consistency’s sake) available here at the site, which considers not only stolen-base runs but also other manner of base advancement.
To establish what “elite” run production is both for outfield defense and baserunning, I averaged together the top-10 leaders by each measure over the past five years — which is to say, I found the top-10 outfield leaders for UZR-plus-positional adjustment from 2012 and averaged together their totals. Then I did the same for 2011, 2010, etc. Then I averaged together all five years’ worth of those averages. After that, I found the top-10 leaders in 2012 by baserunning, and averaged together their totals. Then I did the same for 2011, 2010, etc. Then I averaged together all five years’ worth of those averages.
Here’s what I found:
For defense, the average top-10 leader has saved 15 runs, or 1.5 wins, relative to league average over the last five seasons. For baserunning, a top-10 leader has been worth ca. 8.0 runs per season over the last five years.
So, broadly speaking, we can say that the upside for a player with elite speed — in terms of defense and baserunning — is something like 20-25 runs, or 2.0-2.5 wins.
Notably, not one player appears on all 10 of the top-10 lists considered. Michael Bourn leads all players, appearing on seven of the 10. Brett Gardner appears on five lists. Jacoby Ellsbury, Ben Revere, Ichiro Suzuki appear on four each.
Whether he’s the league’s fastest player, Michael Bourn has consistently generated the most wins by those means — outfield defense and baserunning — that we would generally associate with speed. Since 2008, Bourn has been worth about 12 runs per season defensively (that is, UZR plus his positional adjustment) and just under nine runs as a baserunner — for a total of ca. 21 runs (or, 2.1 wins) per annum. That has allowed Bourn to augment his just slightly below-average park- and league-adjusted batting line over that five-year stretch and average roughly 4.0 wins total per year.
Whether Billy Hamilton can approximate Bourn’s success — either with his legs or with his bat — remains uncertain, obviously. A full-time job and league-average bat would likely place him in the four-win range with Bourn. To profile as a roughly league-average (or, two-win) player — with Bourn-like speed numbers — would actually be rather easy: neither Clint Barmes (62 wRC+ in 493 PAs) nor Brendan Ryan (61 wRC+ in 470 PAs) nor Drew Stubbs (64 wRC+ in 544 PA) managed to produce as few as -21 runs below average, despite all posting miserable batting lines in a large number of plate appearances. Thus, were he to bat like any of that triumvirate, Hamilton would still finish at roughly two wins above replacement — as long as he were able to produce speed-related runs at the same pace as Bourn, of course.