he was called the director of pants and picnics for a reason.
Allen is widely credited for bringing Redskins Alumni back into the picture - something Snyder had worked hard to destroy. We've had the largest home comings we've had in a while, and a number of Redskins Greats have come back into the picture in a number of ways.
He's also credited for a huge turn around in the way Fed Ex Field has operated. From beefing up security, to opening lots earlier, to bringing in more people to control traffic, more people at the gates, making the gates run on metal detecting wands instead of physical pat downs, more people running the concessions. He also brought in a bunch of giant TV's at the end of the 2012 season so we could all show up earlier and watch the other games. Was pretty cool.
I don't know how much credit he gets for the these two, but they happened under his watch: automatic seat upgrade program, creation and utilization of fan captains (there's at least 2 of us on the board that are fan captains

)
Also a bunch of upgrades (ribbon board, new tv) and they've fundamentally changed the way they utilize the tv's after many complaints. Again, not sure how much of that was Allen himself or stuff set in motion by others that just happened under his watch.
There's more, I'm sure.
He's done a lot for the organization. When it came to acquiring talent, my understanding was he made the contracts work but it was Shanahan that decided who to bring in/kick out.