"Frankly, he's grown up a lot," Phillies general manager Ruben Amaro Jr. said.
"He's come leaps and bounds," pitching coach Rich Dubee said.
The Phillies and Kendrick agreed Sunday to a two-year, $7.5 million contract, covering the 2012-13 seasons. The deal replaces the one-year, $3.585 million deal he signed last month to avoid salary arbitration. It leaves him with just one season of salary arbitration remaining before he becomes a free agent following the 2014 season.
"I'm very excited," Kendrick said. "I think for any ballplayer, a multiyear deal is good. Obviously I'm excited for myself, my family. It's pretty special. Now we put it behind us and concentrate on the field."
Kendrick, 27, went 8-6 with a 3.22 ERA in 34 games (15 starts) last season, shuttling between the rotation and bullpen. He is expected to open this season as the team's long man, although he is the first choice to move into the rotation should somebody suffer an injury. Dubee also said he might experiment with Kendrick pitching in the seventh and eighth innings as a late-inning reliever.
Regardless of where he pitches, the Phillies wanted to sign Kendrick through next season so they have more cost certainty with their 2013 payroll.
"He's been very durable," Amaro said. "I knock wood on that one. He's won a lot of games for us. He's played some pretty important roles for us, particularly as a starter, but he's also adapted pretty well to being in the bullpen as well. He provides a variety of roles for us and in some ways some insurance."
In the past, Kendrick frustrated Dubee, but he worked hard on developing his changeup and cutter, which he needed being a one-pitch pitcher -- sinker -- his first few years in the big leagues. Kendrick also began to work out diligently with Roy Halladay, who proved to be a tremendous influence on him. With his mental approach and secondary pitches improved, Kendrick found more success on the mound last season. Left-handed hitters had hit .320 with an alarming .913 OPS against him from 2007-10. They hit just .234 with a .763 OPS against him last season.
"His self-esteem has grown," Dubee said. "He's much more aware of being responsible for his actions, for his workouts, for his preparation. Before, he kind of had to be led. I don't know if it's some of the influence from our veteran guys. He just had his first child, and maybe he's getting to the point where he has grown up and is getting more responsible. Kyle has done a tremendous job in those areas and really established himself as a very valuable piece to us."
"I think I've matured," he said. "Maybe it hasn't shown, but I feel like I've grown a little bit -- developed pitches, learned from the older guys, just try to get better every day. ... Whatever they want. I'm happy. Wherever they want me to be, I'll take the ball like I've done before. If it's start, middle, seventh, eighth -- I'm happy wherever, as long as I'm pitching."
Todd Zolecki is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.