Why is Grigson gone?
Colts draftee still on team:
2012: 2 still on team
QB-Andrew Luck (1-1)
WR-T.Y. Hilton (3-92)
2013: 0 still on team
2014: 2 still on team
OG-Jack Mewhort (2-59)
WR-Donte Moncrief (3-90)
Out of 21 draft selection spots (7 awarded per season); Grigson managed to find only 4 guys that are still on the team 6, 5 or 4 seasons later (assuming those guys make the 2017 roster!

).
Granted, you could bump that up to five if you include Vontae Davis since we directly traded a draft pick to get him but....
My guess is that number needs to be more like 10 or 12 out of 21 to be a top flight team/GM. Many of your 5th/6th/7th round picks should not probably stick for more than their rookie contract (if that long) but your lower round picks should still be on the team at the end of their rookie contracts.
Anyway, that is dreadful.
How much better would our roster situation be if these guys had turned into at least NFL solid?
OLB Bjoern Werner (1st round 2013)
OG Hugh Thornton (3rd round 2013)
OC Khaled Holmes (4th round 2013)
RB Trent Richardson (1st round 2014)
1st round 2015 spent on a position other than OC (since Holmes worked out)
That is 4 spots that the Colts need to fill right now (Right OG, OLB[RUSH], RB, Whatever we took with 1st round 2015) that we could be looking at other positions if Grigson had just picked better guys (or Pagano developed talent better).
Anyway, I am glad Grigson is gone.
Bonus question. Who are the Colts draftees still on the team that were drafted prior to the Grigson era in Indy? Don't cheat!
Cheers,