I like him better than some of the 5th OF they have. He'd be a decent RH bench bat IMO. I'd go with six OF and add him. Winker, Cast, Senzel, Shogo, Naquin and Ervin. My IF would be Votto, Moose, Garcia, Suarez with Farmer add Barnhart and Stephenson and there is the position group. I wouldn't be afraid to use Senzel in the IF when needed.
Ervin can also run, so if they are looking for a runner on second in extra innngs, he could do that. Then they wouldn't need to keeep strange-Gordon for that. Another plus for signing Ervin.