By my reckoning, you've got 12 teams that have made GM changes in that time span: JAX (Jalen Ramsey, Myles Jack, Yannick Ngakoue), SF (DeForest Buckner, Joshua Garnett), BUF (Shaq Lawson), IND (Ryan Kelly, Joe Haeg), OAK (Karl Joseph), CAR (Vernon Butler, James Bradberry), CLE (Emmanuel Ogbah, Joe Schobert, Shon Coleman, Derrick Kindred, Seth Devalve), HOU (Will Fuller, Nick Martin), NYG (Sterling Shepherd), GB (Kenny Clark, Blake Martinez, Dean Lowry), BAL (Ronnie Stanley, Tavon Young, Matt Judon), and MIA (Laremy Tunsil, Xavien Howard, Kenyan Drake). I haven't checked throroughly to see if some of these guys have been extended already.