It's not even the fact that you are selling players to your rivals, its that you are doing it when it wouldn't hurt you one bit to keep him. You have how many millions in the warchest? My Arsenal mates keep telling me something like 100m. So what's the 6/7m that this sale generates gonna help with lol. Better off keeping him as he's not even a bad player - if you don't believe me on that then you'll see this point proven next season. Plus now you have to look for an extra CB on top of DM, RB and CF.
I respect and adore Wenger but he needs to stop sending players off to teams around you; or at least ship them off overseas. Mourinho wouldn't give you Ba because he knew it would improve your team. Ba: their 3rd choice striker. But with Verm that'll be your 3rd former captain to go to a rival along with Fab and RVP in recent years. This just makes me realise how ****ing well we did to keep Suarez off you and Gerrard off other clubs over the years.
And with Fabregas, even though Wenger is correct in saying he is surplus as of now, you still should have bought him back. I can guarantee a time will come when Rambo and Wilshere and probably Ozil are all simultaneously injured next season and you guys will be crying out for a player like Fabregas again. Yeah he wouldn't be as cheap as some developing youth player but thats beside the point, you have the money and he's easily one of the best players in his position so he'd improve your team immediately.