One of the difficulties with working with baseball statistics is that sometimes the devil is in the details. Failing to carefully consider how a statistic is computed can lead to misinterpreting its meaning. I have discussed this before in the mis-use of "innings pitched" to measure opportunity rather than a measure of outs.
The example below is more complicated, but probably even more pernicious because the problem is less obvious. Let me give an example to start the converstion with a question. Which of the following two players would you rather have come to bat with runners in scoring position given these career "slash" numbers with runners in scoring position*, AVG/OPB/SLG:
Player 1- .322/.383/.496
Player 2- .310/.527/.594
I think most of us would quickly choose Player 2 based on his superior power and OBP. In fact, it isn't really very close based on those numbers. But let me add these two non-standard stats:
Player 1- .278
Player 2- .200
Player 2 gets a hit 1 in 5 times he comes to the plate with runners in scoring position and Player 1 gets a hit over 1 in 4 times. And a similar thing happens when you look at total bases:
Total Bases/Plate Appearances
Player 1- .429
Player 2- .384
So which one would you rather have heading to the plate with runners in scoring position now? I think its Player 1 and not particularly close. What is happening is pretty obvious, Player 2 is walking a lot. Those walks reduce his at bats so that his AVG and SLG are both very high. Certainly an argument can be made that all those walks have value, even with runners on base. But I think what you are really looking for in that situation is a hit, not a walk.
BTW, Player 1 is Kirby Puckett and Player 2 is Barry Bonds. To some extents they are extreme examples. Bonds is way over the top in terms of walks and Puckett swung at, and could hit, almost any pitch anywhere near the plate. But if someone tells you batting average measures "how often" a batter gets a hit, that isn't really true. And if someone suggests that AVG does not reflect walks, that isn't really true either. The impact is indirect, but it is sometimes significant.