I agree with this. It's not just getting batters out it's when you get them out. It's very much analogous to BA with RISP. Edited to add: I'm not a stat-head and I'm sure this can be modified to be more representative of a reliever's performance, for example using win-probs, but the concept remains the same. It's more important to get the more important outs and less important to get the less important outs.