"The alternative is surgery," Angels manager Mike Scioscia said. "It certainly is a long recovery. It puts you out for not only this season but the lion's share of next season, possibly all of next season. So I don't think it's anything we're going to rush into."
The Angels have another starting pitcher, Andrew Heaney, who is also hoping the non-surgical route will allow him to avoid Tommy John surgery. Heaney received a platelet-rich plasma injection to help heal his damaged UCL in late April and will be re-evaluated around the second week of June, with hopes he can resume throwing by then.
PRP injections involve a patient's own blood being drawn and filtered to concentrate the platelets, which attract healing growth factors that can speed up the recovery process. Richards' procedure involves taking stem cells from his bone marrow or fat tissue and injecting them into his UCL to serve the same purpose.
Richards was already at the point when Tommy John surgery would've potentially knocked him out for the entirety of the 2017 season, so taking the extra time to try this route, even if he ultimately has to have Tommy John surgery, may not delay his actual return to the Angels.
Heaney had similar sentiments about his course of action.
"There's been a lot more research coming out, as far as guys trying to [return from Tommy John surgery in] one year, the 12-month program, and it's just not really healthy; it's not the way to go," Heaney said. "So I think a lot of people are considering TJ rehab to be 16 months. That's the safe route. That's what guys are trying to trend towards. So for me, even if I would've [had surgery] two weeks ago, maybe I get back by August . And then you're looking at having two months, straight out of rehab. At what capacity are they going to let me throw?"
Richards was on his way to being one of the game's best pitchers in 2014, winning 13 games and posting a 2.61 ERA in his first 26 starts, until he ruptured his left patellar tendon at Fenway Park in Boston on Aug. 20. He bounced back to have a strong '15 season, going 15-12 with a 3.65 ERA in 207 1/3 innings, and entered this season as the Angels' Opening Day starter.
More than a year fully removed from knee surgery, Richards was confident he could take his game to another level this season. The 27-year-old right-hander already threw the hardest four-seam fastball among Major League starting pitchers, backed it up with a wipeout slider and knee-buckling curve, finally grasped a low-90s changeup and was excited about reintroducing his two-seam fastball with a more stable landing leg.
Richards made six starts, posting a 2.34 ERA while striking out 8.8 batters per nine innings, before an MRI revealed a tear in his UCL.
"I never threw one pitch that made me think, 'Oh my god, my arm is done,'" Richards said shortly after his UCL tear was announced. "It was just kind of something that progressively snuck up on me and kept going. There was never one pitch where I felt anything specific."
Scioscia said Richards received input from "numerous sources, both players and doctors" and added that the non-surgical route was "solely his decision."
"It was done just in hopes of having the best outcome, of having him be healthy," Scioscia said. "I don't think you want to jump into any kind of surgery, let alone a surgery to the magnitude of a Tommy John procedure. I think for Garrett's best interest, it's best to take this course and see. If it doesn't work, you have to re-evaluate it at some point."
Bartolo Colon famously underwent stem-cell therapy in March 2010, then came back strong with the Yankees in 2011 and continues to pitch well in his age-43 season. Colon spent all of 2010 recovering from the procedure, but he was 37 years old and was using it to repair both a damaged elbow ligament and a torn rotator cuff.
There is generally less information about the effectiveness of stem-cell therapy as opposed to PRP injections, which have been undergone by the likes of Zack Greinke, Masahiro Tanaka and several others. Stem-cell therapy usually requires a longer recovery.
A high-grade tear of the UCL, as in Richards' case, typically means a tear greater than 50 percent. One medical expert said stem-cell therapy for pitchers with more than a 50 percent tear is "not likely to give good long-term results."
"Quick fixes are fraught with danger," the medical expert said. "Time will tell."
But Richards, who is not eligible for free agency until after the 2018 season, can always opt for Tommy John surgery if the treatment does not work.
Said Angels general manager Billy Eppler: "We'll just measure this as the days on the calendar go by."