For some reason, run defense from the RDE position is really in vogue this off-season on this board. It's not that important.
Look at what happens when a team gets a Freeney-type guy: he becomes a 3 down player and the team works to find talent to surround him with.
Now, look at what happens when a team gets an Ayers-type guy: the team works to make sure he sees as little playing time as possible.
I believe that the plan is for Smith to play nearly every down as soon as possible. Phillips was brought in in case he's not ready right away. Ayers is not in consideration for starting, unless his training camp is mind-blowing.