|Now that Ivan Rodriguez is off the disabled list and once again terrorizing opposing baserunners, baseball pundits and talk-show callers can once again debate one of the most often-posed questions of the past few years: Who's the best catcher in baseball today, Rodriguez or Mike Piazza?
Mainstream baseball analysts, generally enamored with "all-around players", tend to favor Rodriguez. Sabermetricians often come down on Piazza's side, for two reasons:
1. Piazza's level of offensive production as a catcher is unprecedented in baseball history.
2. While the two catchers' contrasting defensive reputations are generally based on their control (or lack thereof) of the running game, studies about basestealing lead us to believe that the running game really isn't all that important.
I'm a big believer in the first reason. Piazza's offensive numbers are positively eye-popping for a catcher, and despite Rodriguez's recent fine years at the plate, there's no question that Piazza has been the better hitter.
But the second reason deserves more scrutiny. For one thing, it's overstating the conclusions of earlier studies to make the blanket statement that the running game is never important. Even if you don't expect control of the running game to make a big difference for most catchers, Rodriguez is clearly the very best in the game at gunning down would-be basestealers, and Piazza is one of the worst. Isn't it possible that we'd see a meaningful difference in value between the two extremes on the catcher arm spectrum? Maybe even enough to close the offensive gap between the two?
To answer those questions, we first need to figure out the defensive benefit of catching a runner stealing and the cost of allowing a successful steal. To do this, we'll bring out the run expectation table. This table tells us, for each of the 24 possible bases/outs situations, the average number of runs that score from that situation. Here are the numbers for 1998-2000:
Bases 0 out 1 out 2 outs
empty 0.56 0.30 0.12
1st 0.95 0.58 0.25
2nd 1.20 0.72 0.34
1st, 2nd 1.57 0.99 0.46
3rd 1.46 0.99 0.39
1st, 3rd 1.91 1.24 0.54
2nd, 3rd 2.09 1.48 0.63
loaded 2.41 1.66 0.81
For example, with a runner on second base and nobody out, teams score an average of 1.20 runs the remainder of the inning.
This table lets us easily compute the cost of a SB and the benefit of a CS in the various situations in which they can occur. For example, if you start with a runner at first base and no outs, and you allow that runner to steal second, that costs the fielding team an average of 0.25 runs (1.20-0.95). If that runner is caught stealing, the fielding team gains an average of 0.65 runs (0.95-0.30).
Of course, not every stolen-base attempt occurs with a runner on first and no outs. To estimate the values of SB and CS in general, we need to know how frequently they occur in each of the bases/outs situations. For that, we'll use data from Retrosheet (www.retrosheet.org) from 1978-1983. (Yes, the numbers are a few years old, but they're easy to get and use, and it seems a reasonable assumption that the proportion of basestealing attempts per bases/outs situation hasn't changed drastically in the past 15 to 20 years.)
I won't show all the numbers here, but when you average the cost of a successful steal in a situation weighted by how often it occurs in that situation, you get a resulting expected defensive cost of a steal of .16 runs. Doing the same thing for a caught-stealing yields an expected defensive benefit of .49 runs for a caught stealing.
This analysis suggests that the price the offense pays for a caught stealing is three times the benefit they get from a successful steal. Another way of looking at it is that in today's game, you need three successful steals for each caught stealing (a 75 percent stolen-base rate) just to break even. Previous research had suggested that the SB/CS break-even point was closer to 2-to-1, but it looks like today's high run-scoring environment creates an even tougher standard than that. It goes back to a baseball truism that we discussed last year: Outs are precious, much more precious than extra bases.
Stolen-base strategy would make a good column by itself, but let's get back to our catchers. We want to use the SB and CS values we just computed to estimate how many runs a catcher's arm saves or costs his team. We'll do this by charging the catcher .16 runs for each stolen base he allows, and crediting him .49 runs for each time he catches someone stealing (or Catcher Pick-Off, CPO, which we'll treat the same as a caught stealing). Here are the five most- and least-valuable catcher arms since 1998 (including this year through Sunday's games):
Rank Catcher SB CS CPO SB Runs Prevented
1. Ivan Rodriguez 96 101 18 43
2. Henry Blanco 93 84 2 27
3. Mike Matheny 159 94 7 24
4. Brad Ausmus 174 95 2 19
5. John Flaherty 225 108 4 18
141. Darrin Fletcher 273 76 0 -7
142. Dave Nilsson 107 19 1 -8
143. Todd Hundley 204 48 0 -10
144. Eddie Taubensee 232 46 0 -15
145. Mike Piazza 371 88 0 -18
No surprises here. Rodriguez ends up at the very top of the list by a wide margin, while Piazza sits at the very bottom, with over 60 runs separating them over the three-plus years considered.
So is the 60-run defensive advantage Rodriguez enjoys enough to make up for Piazza's offensive superiority? We can evaluate the offensive production of the two by using Total Baseball's Batting Runs (BR), which measure how many runs a hitter contributed beyond what a league-average hitter would produce in the same number of plate appearances. Adding the Stolen Base Runs Prevented (SBRP) measure from the previous table to Batting Runs gives us a more complete statistical picture of the two players:
Year BR SBRP Total Year BR SBRP Total
1998 43 -1 42 1998 15 18 33
1999 28 -4 24 1999 19 18 37
2000 41 -11 30 2000 27 4 31
2001 9 -2 7 2001 5 3 8
Total 121 -18 103 Total 66 43 109
When you combine the value of their arms with the value of their bats, Rodriguez gets the edge for the past three years, the edge for each of the past two full seasons, and the edge so far this season. So yes, it is possible that the Rodriguez's superior arm is enough to make up for Piazza's superior bat.
I should note that this is not intended to be a career evaluation of the two players. I'm focusing on just the last few seasons because I'm interested in figuring out who the better player is now. There's no question that Piazza has the more valuable career to date. During the mid-1990s, Piazza's superiority over Rodriguez with the bat was so pronounced that no amount of caught stealings and pickoffs could make up the difference.
I'm also not claiming that this article represents the final word in catcher evaluation. There are many issues I'm not going to address here, such as all the other things a catcher does besides controlling the running game, the role a pitching staff plays in influencing a catcher's SB and CS numbers, and whether there are extra benefits of stopping the running game not measured here, such as preventing hit-and-run plays.
So who is the better catcher right now? It's too close to call. But I hope the lesson learned here is that catchers' ability to throw out basestealers can make a significant difference, and that ability shouldn't always be dismissed as part of the "unimportant" running game.
The team of writers from the Baseball Prospectus (tm) will be writing twice a week for ESPN.com during the baseball season. You can check out more of their work at their web site at baseballprospectus.com. Michael Wolverton can be reached at firstname.lastname@example.org