coach comments nicely wrote:
I think the major reason for the decrease in times is due to him changing to the marathon. He isn't really doing any shorter speed workouts. He is mainly working on endurance based workouts for a fall marathon.
Except that plenty of other runners train for fall marathons and do much better in shorter track races than Solinsky just did. Just last year, Ritz ran a 13:09 5000 in June before his 2:09 in the fall. (That's actually a faster pace than Solinsky ran in his shorter race.)
And guys who ran in the 2:12-2:14 range last fall (that seems to be the range people are imaging for Solinsky) also ran faster in the spring and summer. Bobby Curtis ran a 13:24 5K in May, Tegenkamp ran a 13:35 in March, Christo Landry and Ryan Vail both ran a 27:5x 10k in March. All of those times grade out as far superior to an 8 minute 3000. (To be fair I didn't see any marathoners running a 3000, which is both shorter and less common. I have no idea what training benefit Solinsky was looking for by running it.)
Basically, I'm not sure you can just chalk it up to marathon training and dismiss it as a real cause for concern.