So I thought I'd check, after another superb start from James McDonald last night, how his speed held up through eight scoreless innings.
As you may recall, there were some serious concerns about his stamina in his first starts for the Pirates. Granting that he hadn't really been worked properly, he was still seeing a distinct dropoff in ability to reach his top end (94-5 mph) after 70-75 pitches. But last night was different. Per Pitchf/X, his speed was fairly consistent all game - but at a lower velocity. He maxed out at 93.1, while his max was 95.4 (!) in his second Pirate start.
I think the results speak for themselves: not only was he more effective, but he also lasted a bit longer. There's still a certain dropoff after ~70 pitches (see that string of 91-and-under pitches in the seventh inning), but I think that a smaller dropoff makes for more effective pitching - for a Major League hitter, a drop from 95 to 91 looks very hittable, while the drop from 92+ to 91 is insignificant.
At any rate, I think that McDonald has pretty effectively answered our questions about getting stretched out. I'm happy to trade a couple early MPH for more late-inning effectiveness.