It's one of the oddities of baseball stats that, the better a catcher is at throwing out runners, the fewer he will actually throw out. This is simply because fewer players will try to steal: if you have an absolute laser, and gun down anyone who steals, no-one will try it, and so you'll end with zero caught stealing. A high CS% doesn't necessarily mean you're great: it's can also mean you're simply better than baserunners think. It's the same way Jason Kubel piled up a franchise-record number of outfield assists last year. He didn't have a cannon, but it was better than opposing players thought, and a goodly number paid the price.
If you're to analyze a catcher's arm, you probably need not only to look at what happens to runners who steal, but also the overall number of attempts. Last year in the majors, there was one SB attempt for about every 10 innings caught (9.93, to be exact). Montero caught 1,190 innings, which means there should, on average, have been 120 attempts. There weren't. There were only 76. It feels like Montero deserves credit for the 44 times he apparently "scared off" the opposition from even attempting to steal, as well as the 32 times he gunned the runner down. Aw, what the heck. Let's see how that compares with other everyday catchers.
The table below shows the top 30 in terms of innings caught last year - that's everyone with 600 or more innings behind the plate. For each, we show the innings, how many stolen bases that "should" mean, the actual numbers of attempts, and the difference - those "put off" from running. If we assume those would have succeeded at the same rate as those who tried, we can work out a number of stolen-bases "saved", so we don't double-count those who were dissuaded but would have been caught. Add that to the number caught stealing, to get a total of stolen bases prevented (SBP). Finally, adjust for playing time, to give us stolen-bases prevented per 1,000 innings caught.
tl;dr? The table shows the catchers, ranked by the rate at which they prevented stolen-bases - either by throwing out the runner, or dissuading runners from making any attempt, by the threat of doing so.
What can we learn from this? Firstly: there's a reason Molina has won the Gold Glove at the position, the past five years in a row, and it's probably a legit award [unlike some Gold Gloves we could mention]. However, Miggy is really not that far behind, with he and the Reds' Hanigan both virtually as good at restricting the overall running-game as Molina. At the other end, the least "scary" catcher in the majors is St. Buster, with 27 more runners than expected trying to steal against him: however, his CS% was pretty respectable, salvaging his numbers a bit. The same can't be said for our potential backup, Barajas, who is dead-last - and it's not even close.
Of course, there are limitations to this method. The number of attempts at stolen-bases depends not just on the catcher. Pitchers play a part, and certain teams are simply more active on the base-paths than others. For instance, the Padres ran over 200 times last year; the Tigers, 82, so playing the former a lot would naturally lead to more attempts, regardless of the catcher [which makes Miggy's numbers even more impressive,. actually]. However, this all pretty much a digression. I came here, really to throw up some numbers on the stolen-base percentage Montero will allow this year Roughly a thousand words later, let me get round to doing so. Better keep it brief.
So, here are Miggy's stats as a catcher for each year in his career to date:
What you can see here is how Montero's defense against the stolen base has improved dramatically since the first couple of years - he's now throwing out close to twice as many base-runners. As a yard-stick, the league average has ranged from 25-29% over that time. So, he has been better than for the past three seasons, and over the past couple of years, he has been among the best in the business. However, he's not exactly going to be under the radar any more, and we've seen a marked drop in the rate of attempts since 2010. Even if his rate remains about the same, you might see fewer efforts, and so, fewer thrown out.
The other key thing that will play into this is Montero's stamina. Over the past two seasons, he has been an absolute iron man by catcher standards, playing more often than just about anyone else. Can he keep that up for a third consecutive season? The Diamondbacks certainly hope so: you could argue that the drop-off from our starter to replacement is bigger at the catcher's spot than anywhere else on the diamond. But most years, you only get three or four catchers who play 140+ games: what are the odds of Montero being able to be one of them, three seasons in a row? Obviously, the less he plays, the fewer he can throw out.
So, what do you think? Can Montero throw out another 30+ base-runners this year? Or will his numbers slip, for one of the reasons discussed above?