After thinking about it some more I have to go with David, even though I voted Rex.
RB is probably the easiest position for a guy to step up and at least hold down the fort. And we have three very touted freshman here on the roster.
Fonzie is very important and it'd be a big blow to the defense to lose him. But David is unique and can't be replaced with any LB on the roster. Maybe another CB will step up, if Fonzie were not here. A lot of unknown names, but it is slightly more likely than at LB. David's presence at LB gives this defense an edge that it stands zero chance of duplicating without him.
Our DT depth is simply too great for Crick to merit consideration. Caputo has been solid while healthy, but not extraordinary. And I suppose he is undersized.
I can see why people would want to go with Taylor here, but I just don't see that at all. We weren't really without Taylor last year, we forced through it playing an injured Taylor. The one game we really committed to and prepared for without Taylor, was Colorado, with Cody. The real struggles came when we had to go with Taylor injured. Without Taylor, Brion steps up and we have to build around him. Yeah, there'll be freshman mistakes, but Taylor is going to have sophomore mistakes this year anyway. Comes with being new to the QB position compared to most other guys. Taylor has ability, but he's yet to put it together yet. A huge campaign this year could change the answer for next year. But as of now, I don't see Taylor as being on the radar for this poll question.