Mel Tucker came in highly recommended by the two most successful Michigan State coaches in recent years: Mark Dantonio, who stepped down last week, and Nick Saban. Even with Dantonio's blessing, he is expected to bring heavy changes to the coaching staff.
On Friday, it was reported that Tucker was going to bring in an entire new staff to East Lansing. As head coach at Colorado last season, it isn't that surprising that he'd look to bring many of those coaches along. A head coach is also well within his rights to make his own hires, especially if he's implementing a new system. It is fairly common for them to retain a few guys from the previous staff though, as well.
As it turns out, Tucker will be retaining at least a few coaches to bridge the gap between the staffs. Mike Tressel, who served as the interim head coach in the days between Dantonio's resignation and Mel Tucker's introduction, will be back. He was Dantonio's longtime assistant and right-hand man, so that isn't a huge surprise. He was defensive coordinator and linebackers coach last season, but his role has not been specified on the new staff. Ron Burton, the staff's defensive line coach, who focused solely on defensive tackles in 2019, will also return, once again as defensive line coach.
As of now, those are the only two that have been announced as back for 2020. One coach whose future with the team has not been discussed, but who has serious Michigan State roots and support from his players, is defensive ends coach Chuck Bullough. He was a star linebacker for the Spartans, and later served as a graduate assistant at MSU under Saban and Dantonio, after a five-year NFL career. He spent the last two seasons coaching defensive ends under Dantonio and Tressel, and players want to see him back. One of the team's top defensive lineman, Jacub Panasiuk, went so far as to say that he'd be "gone" if Bullough isn't retained, in a since-deleted tweet.
Jacub Panasiuk thought better of that tweet and deleted it shortly after sending it. He is clearly serious about supporting Chuck Bullough though, and has sent other messages in that vein.
He also retweeted this message:
Panasiuk would be a big loss for Michigan State, if he was serious about that ultimatum. The two-year starter has played in 38 games for the Spartans, starting 24. In 2019, he recorded 34 total tackles, 11 tackles for loss, and five sacks.
We'll see if he goes through with it. It would be a bold move with just one year of eligibility remaining.