I was watching a bit of Reds vs Phillies yesterday. The commentary turned to Cesar Hernandez after getting on base. Hernandez is young (26) and definitely fast, 17SB last season (19SB in '15), but not a particularly good base runner and while 17SB in '16 might look good, he got caught 13 times as well. So he's really not a good base-stealer either. They said it's also partly because there's no real way to practice base stealing. A player can take batting practice and work on his swing, or a fielder can work on various drills to get better. A player looking to steal more bases efficiently is at a disadvantage mostly due to not being able to replicate any given pitchers' subtle moves before a pitch. I suppose one can look at video to spot the best time to run on a pitcher before the game, but to practice it is impossible. This isn't so much of a counter-argument to what you're saying, you make some strong points, but I think it's worth noting. I also like a catcher who can pick off a runner leading ( I've seen both Vaz & Leon do this). That may not count under CS%.