I was happy to see that FitzSimons' time was due to a spill -- he had a very unlucky first year at Villanova and I was afraid he re-injured himself. I cannot wait to see this guy healthy and confident -- 1:45 / 3:42 is in the offing for him, or I'll eat my hat.
On Bowers, I don't know the specifics of the injury, other than being told that he's regaining fitness from an unspecified previous injury. It might be that someone like Ellison or Hines runs the 400 leg early in the indoor season, with Bowers taking over later in the season (say, by the Penn Relays).
Tetreault led off last year in the 1200 leg and ended the season strong, so I am assuming that Marcus will have him in the 1200 mix this year. McEntee is a very mature runner (despite his class standing), so my guess is that Marcus trusts him to anchor. Otherwise he could put McEntee in the 1200 and make Tetreault anchor. From what I understand, Marcus was going to use McEntee last indoor season at the NCAA DMR (in the 1200 leg, IIRC), despite McEntee being in his first semester, but when Gibney seemed strong in the 1500 final, Marcus decided to put Gibney in the anchor and seat Tetreault in the 1200, effectively bumping McEntee off the DMR. The point being, I guess, is that Marcus had enough faith in McEntee in 2011 as a first-semester freshman to have him in the DMR at Indoor Nationals. McEntee has done nothing since then but show ever increasing signs of big-time talent. Hence, I think Marcus will not hesitate to stick him in the 1600 anchor.