It's definitely going to happen, Haye's not going to want to give up the WBA strap now and the only way to hang onto it is to fight the mandatory against Ruiz. It could be a bit of a hard sell, Ruiz isn't exactly the guy of fighter that people rush out to watch, but the build-up should be very entertaining and if Haye knocks Ruiz out that'll get him a lot of brownie points.
I don't mind this fight. Ruiz is a legitimate HW and even though he's been around forever, he'd still likely beat guys in the top 10, 12. Could be a good fight for Haye. Ruiz is a nice name and someone that he could look really good against. A good fight to get some more recognition at HW before a showdown with a Klitschko.
i don't think it will be a bad fight. ruiz will not be able to tie haye down easily, so i doubt it will be a hugfest- not until late in the fight at least.