Winthrop alum here. Kelsey is a very good coach and I'm sad to see him leave, but happy for him to take that next step. He did a great job turning around a Winthrop program that had declined after being a perennial NCAA tournament team under Greg Marshall.
Kelsey coached Winthrop to the last four Big South title games. They finally got the W this season and made the big dance for the first time since 2010. Kelsey's teams are uptempo, high scoring, shoot a lot of threes. Runs a modern styled offense. Likes to put shooters all over the floor and is generally willing to sacrifice size for players who can stretch the defense.
He was mentored by former Xavier and Wake Forest coach Skip Prosser, whom he was very close with. Prosser's sudden death hit him hard and he actually had to take a break from coaching to cope with the aftermath. Prosser's son, Mark, was an assistant coach for Kelsey at Winthrop and may end up taking over as head coach.
I know it's cliche, but Kelsey is a process orientated guy who looks at himself just as much as a teacher than as a coach. He'll bring in guys who buy in and he'll get them to play hard. Obviously he was never going to get top talent at a school like Winthrop so he searched high and low for diamonds in the rough. Best example was probably Big South player of the year Keon Johnson. Everyone was focused on the fact that he was only 5' 7". Kelsey realized the kid can flat out play so he went after him. Johnson said he ended up going to Winthrop because Kelsey was the only head coach who personally visited Johnson at his home. Kelsey also successfully recruited a few overseas guys, impressive for a small school like Winthrop.
He should do well for UMass.
Should probably post this, since this is what Kelsey is most famous for: