Draft was tentatively scheduled to be the starting strongside LB, but his real value was the fact that he could play all three linebacker positions. Depth, something we still need to see whether or not the Rams have enough of at LB.
Of course, the critic could look at the situation and say that Draft didn't make the Rams linebackers any better last season or the season before when he was getting plenty of playing time. The real upgrades to the Rams linebacking unit is the addition of a true MLB in James Laurinaitis and moving Will Witherspoon back to his natural fit on the weakside. You've got to honestly ask yourself what the dropoff is between Draft and Vobora and Grant.
The move makes David Vobora, the 2008 draft's Mr. Irrelevant because he was the final overall selection, the starting SLB. However, I would expect Larry Grant to either take that mantle or get something close to a 50-50 time share at SLB given his ability as a blitzer. Grant, out for now with a knee injury, would probably be the primary backup at MLB, should Laurinaitis miss time. Or even Vobora. Chris Chamberlain is the primary backup to Witherspoon. Quinton Culberson, brought in to replace Draft, will mostly be a special teams guy, but profiles as an outside LB.
Salary drove the decision to release Draft, specifically his reported unwillingness to take a $300K pay cut. You can look at that from either side. From Draft's side, why take a pay cut when you've been identified as a contritbuting member of the team. From the organizational standpoint, a pay cut gives the team the flexibility it needs to field the best team they can. Veteran players agree to have their contracts restructured all the time, usually it's the big contracts we think of though.
What it most immediately indicates to me is that the Rams are finding every inch of salary space they can in order to make further additions to the roster, whether those additions are planned or on an as-needed basis remains to be seen.