Sets like this will probably help. I think you just need to develop more confidence in your pacing. My feeling is maybe yesterday you took a look at the clock early on and decided "uh oh, I better slow down a little." Maybe you really didn't need to slow down. As you swim distance more you'll get a feel for what pace you can maintain and this is a function of how your body feels, not what the clock reads. Personally, I rarely look at the clock or want someone to give me signals about my pace. I know not everyone feels the same way, but I feel like if I'm going too slow I probably already know it and there's very little I can do to speed up. Conversely, if I'm going fast it's probably because I'm feeling good and can go that fast. It ain't perfect. I still have races where I think my pace is good and then the piano hits in the back half, but I think the more you swim distance events the less this will happen. Well, yeah, you need to be in good shape, too!
Sets like this will probably help. I think you just need to develop more confidence in your pacing. My feeling is maybe yesterday you took a look at the clock early on and decided "uh oh, I better slow down a little." Maybe you really didn't need to slow down. As you swim distance more you'll get a feel for what pace you can maintain and this is a function of how your body feels, not what the clock reads. Personally, I rarely look at the clock or want someone to give me signals about my pace. I know not everyone feels the same way, but I feel like if I'm going too slow I probably already know it and there's very little I can do to speed up. Conversely, if I'm going fast it's probably because I'm feeling good and can go that fast. It ain't perfect. I still have races where I think my pace is good and then the piano hits in the back half, but I think the more you swim distance events the less this will happen. Well, yeah, you need to be in good shape, too!