Joseph actually has spring training Pitch F/X data going back to 2010, despite never pitching in a MLB game. His best fastball velocity was in 2012, when it was 92.77 MPH on average. This year in spring training, he is back down to where he was in 2010, at 89.60 MPH. The pitches per appearance is roughly the same, so the velocity differences are really strange, and make him hard to evaluate. Not quite 93 MPH is below average out of the bullpen, but it is significantly different (better) than shy of 90 MPH on average. We have just one outing in 2010, and just one outing in 2012, but they were measured at the same park (the Mariners/Padres facility).
We see quite a bit of difference in delivery for those two outings (sorry for the weird formatting):
As you can see, he was coming more out, and he was clearly focused on moving the ball glove side, into righties, away from lefties. How about when he was more straight up in 2012?
This is small sample size, but he seems to not have that cross tilt, and seems to be working more just generally low than glove side. How about in 2013? We actually see that he is further out than he has ever been before, as this comparison chart shows