Chen obviously was going for the NCAA qualifier (I have no idea why, because he should have raced to win). But, nonetheless, Ches leading the majority of the race makes this obvious. Leading takes a ton out of you, a big reason why pacers exist. If you follow, you just go through the motions. If you lead, you set the pace and push the whole time. Ches leading is silly racing in a distance race, and it makes sense that he wouldn't finish fast as a result (which I am sure he knew would happen). Hence, he led simply to get the standard, not to compete for the win.
To the contrary, Cheserek had the best and most opportune position of any runner in the race, but was just not fast enough to run any faster than he did.