This is an easy question, but you keep ignoring all of the obvious answers posted above. Your legs and body are tired. Adaptation is not instantaneous. Either accept the slower recovery runs as part of the process, or incorporate more rest and/or lower intensity until you see the pace you want.
getting slower wrote:
Ok, It doesn't seem to have anything to do with the warm weather. If that was the case, I would be slowing down throughout runs and it would feel hard, but I actually have the exact opposite.
For example, on this morning's run my first mile was a really slow 8:50, and the rest went something like 8:33, 8:24, 8:15, 8:05, 8:07, 8:02, 8:01, 8:04, 7:46. I do dynamic warmups such as squats, lunges, and stretch kicks, but it doesn't seem to do anything as I'm still starting out very slow and staying slow throughout the run. My stride feels very short and choppy at the start, gets a little better throughout but I can never seem to feel completely smooth. I'm not really worried about my easy runs, but Its just weird to me that the pace that feels natural for me on easy runs is much slower than what would be expected, as a lot of the training calculators are saying 7:00-7:45 is my easy pace. I do think my legs are just flat from the mileage, so I'll try taking a down week this week to see if it makes me more springy. But again, I don't get why my easy pace kept getting slower the last time I took a down week.