Rupp is a much better tactician than Tegencamp.
I watched the video of the race at flotrack. Tegencamp got up to the leaders with a bit more than 5 laps to go and then kept cutting himself off to stay behind them. He was lucky to get second, only because one of the first two stopped before he got to the finish.
The other four were battling the last 5 laps, while Tegencamp kept staying behind them. That is fine for conserving energy but at some point you need to make a move to get in front by the finish. The last 180 meters is way too late to be 10 or 15 meters behind, and hoping you are faster than everyone else.
But if you really are faster than everyone else then why not make the pace faster with 5 laps to go. It is, after all, a 5000 meter race. And if you can't hold the pace for 5 laps, then surely you have to be in the front the last lap.