Sacks are not the only way i measure a player of course. But you need to look at some numbers. I brought up pass rushing without talking about run defending because when you need to try to factor is the best run defenders and how much they are paid.
I don't think Flowers is worth 10M. I mentioned a top 40 pass rusher because i need to pick one aspect of his game. If you want to say he is a top 20 4-3 DE in the NFL then MAYBE he is. Now your discounting OLBs and DTs who pass rush which are some of the highest paid people with the pass rush skill set in the game. Also some goes play OLB and DE depending on the package called. So there is some confusion about who does what.
Anyway here are 4-3 DEs I would take over Flower for THIS YEAR.
Ansah, Jones, Lawerence, Bosa, Griffen, Jordan, Ngakoue, Hunter, Ingram, Quinn, Bennett, Mack, Addison, Clayborn (yay), Wake, Clowney, Graham, Lawson, Irvin, Fowler. Dunlap, Garret, Clark, Sheard.
I think are of them have a very good case to be considered better DEs than Flowers. Maybe a few I can be talked out of. The issue is that there is about an even split of 3-4 and 4-3 teams so even if he is one of the top 20 4-3 DEs that doesn't mean what it use to.