Paxton, who was 15-6 with a 3.82 ERA for the Yankees in 2019, underwent a microscopic lumbar discectomy Feb. 5 in which a herniated disk was repaired and a peridiscal cyst was removed.
"I think I've thrown probably 12, 14 bullpens," Paxton told the YES Network on Friday. "It's my back feeling really good. My back is a non-issue. I feel totally healthy, so I'll be ready to go as soon as the season comes about. ... I think I'm back to full strength."
Paxton said he's been doing rehab work at his home in Wisconsin while Major League Baseball has been shut down due to the coronavirus pandemic.
"I was nervous going into it," Paxton said about throwing again. "... It's always different when you get on the mound. So I was really interested to see how it was going to feel the next day and it turned out feeling really good. I never really had too many issues with the back after I kind of got going, but it's been getting better and better.
"The velocity is getting better and better, breaking balls and stuff like that, getting a feel for my pitches, so everything is going really well. I've seen some good results there, so I'm continuing to try and improve over this time, even though we're not playing."