I don't think too many would say JJ is that "athletic", he's more of a power guy I think.

Of the 434 guards who attended the combine since 2003, JJ ranked 304th in athleticism.

[www.nfl.com]

5.23 in the 40 yd, 8'2" broad jump, 26" vertical, 5.02 shuttle (all these are pretty bad compared to other guards)
He did 28 reps on the bench which is good.

As a comparison Joe Thuney:

4.95 in the 40 yd, 9' 2" broad jump, 29" vertical, 4.54 shuttle (Joe Thuney is an athletic guard)
Thuney also did 28 reps on the bench.