What's more difficult to measure is how good of a baserunner a player is. TK once said that Kent Hrbek was a very good baserunner, and I'm sure what he meant by that was that Hrbek could read batted balls well and could judge well whether he'd be able to take an extra base in any given situation. Of course there was that pickoff at second base in the 1987 WS... And when it comes to stolen bases knowing how large of a lead to take and when to make the move are critical skills to possess. Speed can compensate for deficiencies there but only to a limited extent.