Wade is a free PS member and he's going there. Clearly they were excited to get him "a few touches" the first of which was a monster run, after he almost fumbled. He's nowhere near ready, not even close.
My suspicion is you will see Shady and Singletary basically alternate and Gore will be the thumper/change of pace guy. I don't see Yeldon making the team, unless they are going to do it purely based on next year's roster. I just don't see it. I think they had little intention of drafting a back this year and it happened to fall the best guy on their board was Singletary. I can't say yet if I see what they see in him, I don't see the burst to be a good starter in the NFL, but he could prove me wrong. Either way, no ST play from Yeldon and the fact hes not all that special anyway, leads me to think he's going to get caught in the numbers, barring an injury or trade of course. I could see them pulling a late round pick out of him or Gore for that matter. The other guys are effective and valueable elsewhere, its unlikely you are going to get much out of a 4th RB when you have 2 HOF players and a highly regarded rookie in front of them, so they better play ST.
Next year Wade has to stick or he's done, 29 yrs old and don't have the skill set down? You are done. He looks like he could be a helluva return guy, so maybe he has some value there too.