Actually, their run defense got better as year went on last season and became REALLY good in the playoffs. It was their inability to stop the pass that killed them in end. Those DE's they have are great. But once they get stalled at the point of attack, that Tampa-2 is wide open for the taking.
The Colt run D and overall D are very interesting to me.
I think they do an incredibly good job of calling defensive plays.
Everyone in the world knows that they are undersized and mismatch if you play smashmouth football, and the stats support it. But thats the trick.
They ARE easy to run against in most situations, because they are undersized and they play rush the passer and hope you find the QB on the way. They willingly give up the run, because they know that sooner or later they will penetrate, make a play in the backfield and put you in long distance passing situations where they can play that Tampa2 and either get pressure or make you throw under it.
The thing that no one seems to recognize is that they are VERY good at stopping the run in obvious running situations because they play one gap, outquick the OL run D. I have never understood why teams try to run off tackle and have to get past 3-4 guys shooting gaps in short yardage.
It almost seems like some teams walk in saying the Colts suck against the run, so all we need to do is run, and that plays right into the Colts hands. I guarantee the Colts would trade allowing 5 yards a carry in return for one tackle for loss every 4-5 plays, and thats what ends up happening. (Remember the KC playoff game with LJ when Herman Edwards was the coach. Worst game plan I ever saw. They told the Colts we are going to run every play, the Colts overplayed the run, got a stop and then KC was screwed on 3rd and long)
Basically, the Colts are probably the worst run D in the NFL if you make them play it honestly and they are one of the better run Ds if you let them know you are running at them. And I think their pass D is similar too. It gets a huge advantage when down and distance favors them, but is ripped up on 1st and 10 by a patient passers.
The key to attacking the Colt D is balance. Even when it seems that you should just hand it off every play its the wrong thing to do because you force them to compensate. You need to run when they expect pass, pass when they expect run, and basically take away predictability.
IMO, the Colt D is one of the worst in the NFL if you approach it with a balanced game plan and one of the best in the NFL if you tip your hand and give them a good idea whats coming.