Depends on what you think he's going to be. If he can truly fix his k rate and get back to that .250/.350/.450 ceiling with average defense in CF and plus defense on the corners....he's a 3-4 win player. If his k-rate is only marginally fixed, then yes, he's probably only a 2 win player...but that's still fairly valuable, especially for the first 3 year of free salary Jackson (much in that mold of why Barney was valuable coming out of 2011 to 2012). If his k-rate isn't fixed as all...then he's just fully broken and worthless.
I still think he's fixible to the point of getting back to where we hoped he was. Unlikely, but possible.