KANSAS CITY, Mo. -- Rehabilitating an elbow after Tommy John surgery can be the working definition of monotony, and Danny Duffy's experience was no different than that of many who preceded him. When he was going through the process at the Kansas City Royals' facility in Arizona, he would arrive at the ballpark by 9:30 a.m., finish all the work he was allowed by midday, and then hang out by the pool.

The early evenings presented the best part of Duffy’s groundhog days; he would head to the same restaurant for Mexican food, always ordering carne asada to enjoy from the same seat, and he would watch the other Royals do what he couldn’t wait to do again: play baseball.

“I didn’t miss a game,” Duffy recalled. “As painful as it is to watch knowing you can’t play, it’s important to stay on that learning track.”

This was a crucial part of Duffy’s mental and physical makeover, and when he takes the mound against Cleveland on "Sunday Night Baseball" (8 ET on ESPN and WatchESPN), the Royals will either be a half-game ahead or behind Detroit in the AL Central. Duffy is well-suited to bear the responsibility of the moment.

Duffy ranks fifth in ERA (2.47) among all MLB pitchers with at least 130 innings. That's a little ahead of Corey Kluber and Jon Lester, a shade behind Johnny Cueto.

He absorbed a lot while eating rice and beans in baseball purgatory. Before that, Duffy was renowned for his big arm, but also for what he did not know about pitching efficiently, about controlling his effort.