If the NFL lockout does end in the next week or two, free agency is going to be absolute chaos. There are over 400 players who you have just two weeks to sign before the start of training camp. Historically, the Colts try to retain their own free agents before going after other team's free agents, and very rarely sign any big names from other teams.
Matt Williamson from ESPN.com wrote an interesting article about the free agency outlook of the Colts. In it he writes:
To me, [Reggie Bush] would actually be a better option than Addai. Having a backfield of Bush, Delone Carter and Donald Brown would give Indianapolis three extremely different types of running backs. And few teams would be as adept at using these varying skills as the Colts. Bush could be pure electricity in this offense. And Manning would masterfully utilize Bush’s ability to confound defensive personnel. Bush isn’t technically a free agent, but he most likely will become available on the open market.
Reggie Bush in the Colts backfield would be a welcome sight to me. An even more welcome sight would be to see Reggie lining up for the Colts on kick-off and punt returns. He would give the Colts a weapon they don't have on Special Teams and coming out of the backfield, but if it means saying good-bye to Addai, I'm going to have to pass.
Williamson says Bush, Carter and Brown would give the Colts "three extremely different types of running backs." That's true, but can any of them pass block like Joseph Addai? No. Addai is an elite pass blocker at the running back position. More times than not, he is the key to picking up the blitz, and giving Peyton Manning that extra second to fire the ball down the field. He was sorely missed when he was out most of last season with injuries.
The Colts offensive line was terrible last season. They drafted two offensive linemen with very good potential in this year's draft, but they can't be counted on to turn the offensive line play around. The colts needs to have someone in the backfield they can count on in pass protection. Since Manning has been in Indianapolis, this has been a pass first team, and it will continue to be a pass first team as long as he's there.
Joseph Addai fits the Colts system. Reggie Bush would be nice, but only as a back up to Addai. Besides, when was the last time the Colts went out and spent money on a big name free agent?