I've been thinking through the possibilities, and I have a hard time seeing how Bruce Irvin will be able to get on the field all that much this year.
Last year, Bruce played about 43% of defensive snaps in the "Raheem Brock" role. This is what most of us expected to see when Irvin was drafted. Basically, he came in on passing downs as a pass rusher, and also (I believe) spelled Clemons once in a while. The DL seems much more crowded this year. Bennett is listed as the backup to Bryant. Bennett is a very complete DE though and should see the field in both passing and running situations. Avril and Schofield have been manning the other DE spot. When Clemons return he is certainly going to get snaps. Bennett can move inside, but then one would expect Avril to come in on the other side.
Seeing this logjam, the coaching staff has discussed playing Irvin at SAM LB. There are several issues with Irvin getting major playing time at SAM. First, Malcolm Smith is playing well there and has spent much more time in this system as a LB. If it ain't broke don't fix it. Second, Avril has also been mentioned in that spot. I think Avril would still have a problem pushing Smith off the field, but he make as much sense as Irvin does at SAM. Don't forget about Schofield either. Lastly, SAM is a part-time position anyways. Wright and Wagner stay on the field in the nickel and that is very unlikely to change. Those guys are not getting pushed off the field easily.
The way I see it, there are about 50% of snaps at SAM (taking into account nickel), about 50% behind Red, and 100% at LEO end. That's about 200% of defensive snaps. Bennett, Avril, Clemons, Schofield, Smith, and Irvin will all need to draw their playing time from that pool. An even split would have each player on the field for 33% of defensive snaps, but we know that isn't going to happen. While Irvin is easily the most physically gifted player in this group, he is significantly less polished than his competitors at either LB or DE. We don't need to wait for Irvin to "figure it out" on the field with this much talent on the roster. Also, Irvin screwed himself over with the PEDs. He could have competed for and won the starting job at DE. This coaching staff has been serious about rewarding the product on the field rather than draft status or measurables, and Irvin has taken himself off the field this season.
Things change a bit here if the coaching staff gets creative with personnel packages. There has been talk of a Avril/Bennett/Irvin/Clemons DL in pass rush situations, similar to what the Giants have done. We don't know how much the hawks will use a DL like this. There are other guys (McDonald, Hill) that can also line up inside in these situations. Regardless, I still think Irvin needs to get onto the field in non-pass rush situations if he is to hit the second year milestone of playing >50% of defensive snaps.
In addition to having a higher ceiling than these other guys, Irvin also has the advantage of being significantly cheaper in 2014 and 2015 then Clemons, Avril, or Bennett. The Seahawks have an incentive to develop Irvin, but I'm not so sure that means they need him to play a ton this year. Irvin could easily end up playing out the season buried on the depth chart, getting perhaps 25% of total snaps while playing in only the most pass rushy of pass rush situations. On the other hand, he could be a revelation. It'll be interesting.