I hope they able to contribute right away, history says it's pretty difficult for first year JC's. These three all had comparable stats to Kwinton Hinson and he struggled last year despite being far more physically developed than the incoming guys are.
I took a look at the past JC transfers since Dick Bennett was first hired. There were a total of 17 and 10 of them did not last two full years. The only real contributers in rough order were Varem, DJ Shelton, Ivory Clark, Callison,Clifford, and Aden. The jury is still out on Hinson but I suspect he will improve a lot.
I like the fact that Cannon has three years because it was a big factor in Shelton's success. Of course it mattered little for Langston and King who were probably both reaches anyway. I sense that Seltzer (mainly) may have a better feel for JC talent than the previous staff but that remains to be seen.