With an A+ arm, the SB attempts will decrease regardless of managerial settings. I’ve run SB teams before, and against C-D arm catchers will have upwards of 20 SB attempts a game, and against A-A+ arms will only have 2-4 a game typically. That’s with all my runner settings at 5.
Im sure you know this too, but not every A+ arm is created equally. Just like not every A+ fielding or range stat is the same, so some catchers will still perform better. I believe the attempted SB is based on the catchers CSPCT.