There is no doubt that Erik Bedard's last four starts have been monstrously better than his first four starts of the season. Through April 21, Bedard was among the league's worst pitchers. Since then, however:
Bedard's not going to run a .221 average on balls in play the rest of the season. Nor will he prevent all batted balls from leaving the park so he is bound to be somewhat worse than he has over this recent stretch, but he has made legitimate improvements that he can sustain. Those strikeout, walk and ground ball changes amount to a whopping 1.8-run decrease in Bedard's xFIP.
The pertinent question is what has fueled this dramatic improvement. I will spare you the giant graphs to make just a subtle point, but it does look like his pitches --especially his change-- have gotten more consistent in their movement and spin and his release points seems a bit more clustered, but that's a subjective judgment on my part.
As for the actual pitch results, Erik Bedard has four pitches: a change, a primary fastball, a sinking/cut fastball and his renowned curve. One of the changes that's occurred is a much more even usage split between his two fastballs. Before, Bedard leaned on his four-seam over twice as often as his cutter, but of late he has thrown them in equal proportion. Both pitches have seen increased effectiveness along with an uptick of about one mile per hour in speed.
One of the results of better control of his fastball is that Bedard has wrangled himself more pitchers' counts. Bedard has gone from 56% first pitch strikes to 66% and by virtue of being ahead in more counts, Bedard has been better able to utilize his curve ball and he has relied less often on his change, which is good because Bedard's curve is spectacular while his change is not.
Without speaking to Carl Willis or Erik Bedard, there's no sure way to know if Bedard has been making conscious changes that have sparked the good spread of starts. Pitching is fickle and Bedard could turn back into a pumpkin in his next start. The data contains no smoking gun that any of us can hang our hat on and proclaim "a ha! Erik simply needs to continue doing this to succeed." My hunch is that the increased speed and tighter groupings are indications that Bedard is gaining strength and endurance in his first post-surgery work in quite a while. If so, that is encouraging since barring a relapse in his health, Bedard should be able to keep that up and continue being an asset.