Ryu is 0-3 with a 5.87 ERA this year. He has struck out 17 in 15 1/3 innings, but he has also given up six home runs already, tied for the National League lead.

To put that in perspective, Ryu allowed only eight home runs in 152 innings across 26 starts in 2014, his last full major league season.

Ryu's biggest undoing has been the lack of any zip on his four-seam fastballs. All six long balls this year have come against Ryu's fastballs, none of them faster than 90 mph.

While the left-hander has never been an overpowering pitcher, at least he was throwing his fastballs around league average speeds -- around 91 to 92 mph -- before he underwent surgery in 2015 for a torn labrum in his left shoulder.

The procedure wiped out his entire 2015 season. Ryu came back for one start in July 2016, before getting shut down for an elbow debridement procedure.

And three starts into the 2017 season, Ryu, who won 14 games in each of his first two big league seasons in 2013 and 2014, has been a shell of his former self. This year, he's throwing his four-seams at 89.5 mph on average, more than 3 mph below the major league average, per MLB.com.

It hasn't been just the speed. Ryu's average spin rate on his fastballs is 2,083 rpm, while the major league average is 2,209 rpm.

Experts say both fastballs and breaking balls are tougher to hit with higher spin rates, and data suggest that spin rates correlate more closely to swinging-strike percentage than velocity.

After giving up three homers to the Colorado Rockies to take his third straight loss at Dodger Stadium on Tuesday, Ryu admitted he's at least a couple of miles slower with his fastball than he had been in pre-surgery days, but that he feels he's getting better.

"I think the three home runs really were the difference," he said. "I have to cut down on mistakes. I must keep them to a minimum at all times, but I am gradually rounding into form."

Torn labrum surgeries have been called "the career ender" in some quarters, with very few pitchers having returned to enjoy the similar kind of success to what they had before their procedures.

Roger Clemens and Curt Schilling are the two highest-profile success stories. Clemens won six of his seven Cy Young Awards after his surgery, while Schilling suffered a slight tear in 1995 and returned to enjoy the best stretch of his career.

On the other hand, Mark Mulder and Mark Prior, former All-Stars and Cy Young hopefuls, were never the same after their operations.

Dodgers manager Dave Roberts said he's still keeping Ryu -- who also had Tommy John surgery in high school to repair a torn elbow ligament -- on a longer leash, given his injury history.

"He's still coming back," he said. "To expect him to be locked in right now might be a little unfair."

If Ryu can't get his fastball up to speed, then he should at least locate the pitch. If a pitcher can do neither and leaves high-80s fastballs out over the plate, then it's a recipe for disaster.

Ryu might instead be better off throwing his off-speed pitches a little more, namely his changeups.

Ryu gave up a two-run home run to Colorado slugger Nolan Arenado in the first inning Tuesday. Then in his next time up, Ryu didn't throw Arenado any fastballs -- with one slider followed by four straight changeups.

Arenado still hit that last changeup for a double, but Ryu said afterward the changeup is "the pitch I can throw with the most confidence."

Ryu did throw more changeups in his third start than he had in two earlier outings.

Of the 97 pitches against the Rockies, 46 were four-seam fastballs (47.4 percent), and 30 were changeups (30.9 percent).

In his season debut against the Chicago Cubs on April 7, only 15 of his 77 pitches were changeups. His usage rates for the season are 53.8 percent for four-seamers and 23.5 percent for changeups.

According to the statistics website BrooksBaseball.net, Ryu has been more effective, inducing swings and misses with his changeups than any other pitches.

Hitters have whiffed on Ryu's changeups 29.1 percent of the time, compared with just 5.6 percent on fastballs and under 10 percent on both sliders and curves.

With reduced velocity and poor locations, Ryu's fastballs have been hit harder than other pitches. Opponents are hitting .424 off his four-seamers and slugging at a 1,000 clip. When it comes to changeups, opposing batters are only hitting .214, and their slugging percentage is .286.

Heo Koo-youn, color commentator for local TV station MBC, said Ryu has to improve his command for all pitches.

"(Against the Rockies), we didn't really see sharp sliders or curves that dropped inside the strike zone," Heo said. "If he can't get them to below the hitters' knees, then he could struggle again in his next start."

Heo added that since Ryu won't be able to dominate hitters with his fastballs, he must be able to attack the inner half of the plate with more frequency and efficiency, and seek to induce weak contact. (Yonhap)