Let's look closer at the departures of Grimes and Lashlee.
Grimes was making $250k at UConn. When he was previously at Auburn, he made $370k in 2015 and the OL coach he was replacing made $420k. Thus, I would assume he is making ~$400k (or more), so he is probably getting a $150k raise to move to Auburn. You wouldn't move to a place that you worked before for a 60% raise? UConn was not going to be able to retain him.
Lashlee was making $350k at UConn and he was previously making $600k at Auburn. He took a $250k pay cut to go to UConn, and nobody does that unless they were being pushed out of their previous job. It was pretty clear that UConn was a soft landing for Lashlee orchestrated by Benedict, but he wasn't going to stay long. He wanted a P5 OC job, but he didn't get one this year, so he decided to go to SMU. Why?
SMU typically pays their football coaches well as Chad Morris was listed (although not officially as SMU is a private school and salary data is not shared) as the highest paid football coach in the G5. So, I would assume that Lashlee got a decent raise to go to SMU.
Plus, Lashlee is going to work for Sonny Dykes, who is very well connected to football in the state of Texas and he is an offensive minded coach. Lashlee's background is in the spread offense and Dykes background is with the Air Raid offense, so I would think Lashlee is going to have the opportunity to broaden his understanding of offensive concepts. Throw in that he and his wife are from Arkansas and Dallas is relatively close to Arkansas and it's pretty obvious why Lashlee went to SMU.
End of the day, UConn needs to hire up and coming football coaches and keep them as long as possible. When UConn gets the call up to the P5 or when boosters pony up the funds to pay football coaches, we will be able to keep coaches longer.