From a larger viewpoint, we've retained almost all of our starters on a dominant SB winning team. The starters we lost were ones we didn't offer much to, so it was expected and likely prepared for. The FO sees something in the younger guys that got playing time last year, or they would'nt have let guys like GIacommini and Tate go.
One thing our FO and coaching staff have shown they're very good at is back end of the roster churn. They are constantly upgrading our depth, and using cheap or no draft picks to do it. Look at McDonald as an example: he was cut last year, and only showed flashes before that. He came back and played very well, now there's a lot of hand wringing about how we let him go. (For the record, I wanted to keep him as well, but I assumed we wouldn't be able to afford him). So it's not like teams swooped in, poached a bunch of our atarters and over paid them....we've pretty much let everyone go so far, or offered them value contracts that they likely wouldn't sign.
The only real thing to worry about is roster depth in a few areas, and we haven't even hit the draft yet, which is where our FO shines. We have a dominant corps of elite young players, and our FO is doing the obvious: working towards cap space to lock that good core of players up and improve our depth. I'm not worried until after TC when guys might look slow to catch on.