If they don't stretch him out this season then they never will.
Biagini is not some lights out, shut down, overpowering reliever. He's a middle of the road middle relief pitcher.
Yeah he had a great 2016 but that home run rate was probably a mirage and his ERA should probably be closer to 4.00 than 3.00 in 2017, in relief.
Toronto sending him to the AAA rotation for a bit is not an insurmountable hit to the bullpen.