FYI 75 AS/AA is what wifs considers an average catcher.  Therefore if a majority of the league has catchers with less than average ratings in those categories, then you will see above average stolen bases league wide.  Just checked Coop and only 7 teams have catchers with above average ratings in both categories and I would bet there are more stolen bases than the baseline MLB season WifS uses.

Just compared the last completed season of Coop to the 2005 MLB Season (which I've heard a few times from CS is the baseline for statistical comparison...unless they changed it)
Total SB in Coop: 104.2 SB per team
2005 MLB: 85.86 SB per team

Of course, there a million other variables and management styles in HBD that have an impact on SB, but I think a major variable is the lack of "average" catchers in leagues.

My Coop C:  Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Philip Brandt  Career 105 CS, 327 SB.   But he has a career OPS of .826, I'll deal with the SB.

As someone who generally sacrifices bat for defense behind the plate (though one team is going the other direction at the moment) I can tell you for certain that it isn't working as you describe.

The Above Average AS/AA catchers end up with a better percentage, yes, but they do it at the expense of the middle-of-the-road and low-end SB guys. Against them, they (generally) reduce the attempts a little bit and throw a higher percentage out. But against the elite SB guys, you can use a 90+ AS/AA and still get run on more or less at will.

I'd be curious to see some hard data that proves that.  

As would I, and perhaps someone who does more statistical HBD analysis than I can provide it. Without any easy way of mining matchup data though, I suspect it would be very labor intensive.

I decided to check three of my catchers of varying defensive skills/results..  
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Harry Ortiz
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Orlando Bonilla
Hardball Dynasty – Fantasy Baseball Sim Games - Player Profile: Kennie Strange

After about 20 minutes, I decided it would be a ridiculously SSS and quit.  Although Strange was pretty effective against high speed/average BR(85/60 types).   He only had two opps vs the big SB threats and went 1-2.  His 69 AA isn't really a good number but the AS of 82 seems to get the job done.  Bonilla would be the guy to check as he's a legit D-catcher.  But that world will roll in about 3 hours and I'm just not down with checking every game with a SB/CS to throw out a SSS.

Here's the speed/BR of the guys Bonilla threw out:
32/66
98/93
84/81
91/66
89/67
85/58
83/58

A couple would be considered big SB threats.  The rest(save one) are fast with below average BR.