Mack got $90M gtd...I can't see Clowney getting close to that. I think it would probably be ~$60-65M...which is what Lawrence and Clark both got...and maybe not even that much.
It's not my money...but I would do it. The Colts have the money...and I don't think the Colts will find a better player to add to the team in FA...Clowney is a 3x consecutive Pro Bowler with double digit sack upside...heading into his prime...whose skill sets fits perfectly into a position where they have a long-term need.
To put it another way...I would much rather give Clowney a deal and add him to this team to try and win a Super Bowl...than spend that cash on extending guys 1-2 years before they are due. The Colts have a nice 3-4 year window where they can be a lot more aggressive.
Signing someone like Clowney will make a dent...but it won't hurt them long-term. There is a very good chance this team will have left upwards of $80M on the table over this four-year period. Right now, they have to spend $44M in cash next offseason just to get 89% (using OTC and estimating a $10M increase for the salary cap). They will make that up for sure (in FA and extensions)...but they have the flexibility to commit to a player like Clowney. I get being lean during those first two years...but not now.
The key for me would be the draft capital. If it's only one of those 2nds...I am very intrigued.