Rogers is impossible to square up. If you look at his savant page, he routinely rates in the top 99-100th percentile in avg exit velo, 95+ percentile in barrel rate, and also among the top in GB rate. He also walks nobody. So you're getting him into games and he immediately provides a very different look to any other pitcher that hitters see throughout the year, resulting in uncomfortable ABs with lots of strikes and extremely weak contact.
He's not really the guy you put in with a runner on 3rd and < 2 outs to get a much needed strikeout, although he could work if you want to induce a groundball at a defender to come home on or turn 2, it's unlikely he's giving up a deep flyball.
His low velo and arm angle also means he's a rubber arm who never misses time and can pitch whenever.
Finnegan is a fastball-splitter guy, who started locating much better when he arrived in Detroit. Hard to say if that's sustainable, although I would believe you if you told me that Detroit is ahead of the curve compared to Washington when it comes to pitching more effectively. His stuff didn't change at all, although Detroit doubled his splitter usage and limited the fastball, pretty much pitching backwards leveraging his best pitch most often.