Great posts on this.
From the business side, yes the right thing to do. Personally I would have been ok with it either way, at first, if he took a pay cut, as I don't think a restructure was really in consideration, as we would have had the same situation next year. And could he return to form of 3 years ago. Most likely not. The more I thought about it, time to move on.
Health wise and production, still the right thing to do when you really think about it. The past 2 years, he has fought injuries, especially later in the year. Even with some valiant efforts, you could see him struggle. But with no one else to step up, he tried. But also how many times was he on the sideline when he was needed. When he was mostly healthy, he was not making that game changing / saving sack like he used to do.
So would you rather have a player, once dominant that you may be 50% to 70% but not know when those times will be. Or a player that will be on the field 100% even though he is very solid but not as dominant, not yet, as in a draft prospect or even younger FA stop gap type guy. That's the way I look at it, probably because we have to look at it that way now.