I wouldn't be surprised. Crowder is bigger, faster and stronger. Using the same scheme we have in the past with the DTs holding up linemen to help our LBs roam, Crowder should be more dominant. Crowder will dominate eventually in any scheme, where as Zach relies on the DTs to do their jobs. ZT is a decent LB, but his stats are blown up because of the scheme he has played in. If you stop and think about all the tackles Zach makes, how many have been for a loss? (Not a very high percentage.) Thomas makes his tackles downfield -anywhere from three yards past the LOS and deeper. Crowder will make more "big play" tackles. And will probably cause more turnovers because of his size equating into bigger hits, etc.
I know this may piss off some Zach fans, but oh well, it's true. Zach is pretty good-not great. Plus he has taken some punishment. I'm not saying Crowder will definetly beat out Zach by the time the season starts, but he may have the job some time during the season. This could open up another trade to get a decent pick or two for Zach while he still has a little something left.