As a starter, you can't exactly go max velo from the start of the game if you're planning on going 80+ pitches, you'll get tired. For my starts I'm probably a few mph slower in the first few innings, but by the fifth or so inning, I'll start to put more on it. But as a reliever, or especially as a closer, you can be max intent on every pitch without having to conserve anything for later. So psychologically, without realizing it, you might be holding back something back during your starts in order to last longer, but when relieving, you know that you don't have to save anything. It might just be me, but does anyone else notice a velocity increase later in the game? Sometimes, towards the 80, 90 pitch mark I feel like I'm throwing harder than I ever do when I'm fresh. Maybe it's on the adrenaline of the late innings.