The Royals had a productive offense and improved defense, but far too often Duffy and the starting staff were ineffective.
Despite finishing 20 games below .500 and tying for the fifth-worst record in baseball in 2011, the Royals' offense was near the top of the American League. Kansas City's .275 team batting average was fourth in the Majors; its .735 OPS was seventh. The team's 730 runs scored were sixth in the AL.
The Royals' defense, which had been horrid the last couple of seasons, managed a .985 fielding percentage, tied for the third-best mark in the AL. The bullpen was a strength for most of the season, as well, allowing the second-fewest percentage (24) of inherited runners to score.
But the 4.82 ERA put up by Kansas City starters was next-to-last in the league. Royals starters posted quality starts in just 46 percent of the team's total starts, which was third-worst in the AL.
Sometimes, it's hard to pinpoint what needs to improve from one season to the next in order to contend. This is not one of those times.
"That's what we're missing, obviously," Duffy said of the Kansas City rotation as the season ended. "Really, you pretty much said it right there, that's all we really need to be a contender. I plan on doing everything I can to be that missing piece. Hopefully that's what it is. I'm not going to leave [anything] to chance ... I'm going to make sure I do everything I can to be that missing piece, fill that void."
Royals management is also moving to fill the void, obtaining left-handed starter Jonathan Sanchez from the San Francisco Giants. One of Sanchez's pluses is a cumulative 3.75 ERA over the last three seasons.
Bruce Chen was the only regular Royals starter to post an ERA under 4.00 this year. Wins and losses aren't great ways to judge pitchers, but with 16 losses, Jeff Francis was one away from tying for most in the Major Leagues. Both veteran left-handers are free agents.
There were some bright spots in the rotation, though. Luke Hochevar had a strong second half. In 12 starts after the All-Star break, Hochevar was 6-3 with a 3.52 ERA. He finished 11-11, with the promise of filling the staff leader role forecast for him. Felipe Paulino was acquired in May and thrust into starting games again after being a reliever for Colorado. He responded by showing flashes of dominance, striking out 119 batters in 124 2/3 innings.
And there was Duffy. His final numbers weren't all that impressive. He posted a 5.64 ERA in 20 starts before being shut down because of an innings limit in early September. He finished second in the staff in walks, giving up 4.4 per nine innings.
However, there's potential. Duffy has great stuff and proved it by striking out 7.4 batters per nine innings. Manager Ned Yost thinks he can develop into a top-two starter. Detroit manager Jim Leyland, who knows a thing or two about judging talent, was quick to praise the left-hander after the Tigers faced him three times this season.
The Royals have lots of young starters still in the Minor Leagues, guys like Jake Odorizzi, Mike Montgomery, Will Smith and Chris Dwyer. But Duffy is the de facto leader of the organization's young starters by virtue of experience. And it's a position he relishes.
"I plan on really getting after it this offseason, coming back physically ready to be what we need: an extra No. 2, No. 3," Duffy said. "That's my goal, you've got to set your goals high. I'm going to do everything in my power to come back physically ready, strong enough to stay consistent in my delivery."
If Duffy can be that -- a top-three kind of guy -- it would represent a huge boost for a rotation whose ace was the soft-throwing Chen this past season. The Royals need Hochevar to carry his second-half resurgence into next season and for Duffy to take a big step forward.
The Californian planned to work out at a gym with Rockies outfielder Ryan Spilborghs in the offseason, as well as doing pool work at home and spending time watching film of his 20 big league starts.
A lot of that video will show Duffy throwing too many pitches and walking too many batters. The southpaw finished seven innings in just three starts. He averaged just a touch over five innings per outing, but threw an average of nearly 98 pitches. Duffy's goal is to increase the first number while keeping the second figure about the same.
"I really want to go into the seventh, eighth and ninth [innings] a lot next year," he said. "That's what a good starter does. My goal is to average a lot less pitches per start, per inning. I think I can do that if I just practice staying in line. Just keep my team in every game; when they fight for me, I fight right back. That's pretty much the goal every time I go out."
As with all of the Kansas City rookies, simply getting game experience this season will help Duffy with the improvements for next year.
"I got over the whole initial shock of being in the big leagues and now I'm set with that, knowing what you need to do off the field and what you need to do to prepare, to be on the field," he said. "Throwing the right pitches in the right counts and executing as much as you can is what I've got to do now. I think right now it will be a little less of a shock value."
That experience has shown Duffy he already has the stuff to compete in the Majors. But adding some better command could take him -- and the Royals -- to another level next year.
"It's definitely nice to just out-stuff people," he said, "but once I learn how to place a ball where I want to, it's going to be scary."
Adam Holt is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.