"Fresh start, new team; I'm just ready to go out here and play some football," Jenkins said prior to his first practice with the Chiefs Tuesday.
Jon Baldwin was in the same boat as Jenkins after two years in Kansas City. Baldwin couldn't find his groove with the Chiefs catching just 41 passes and two touchdowns in 2011 and 2012 combine.
The underachieving wide outs in systems that didn't fit their styles led to the swap of former first round draft picks.
"This presented itself," Chiefs head coach Andy Reid said. "They lost a big powerful receiver for a time with Crabtree. Jon fits in that role, and we needed a little bit extra kick in there. We'll see if AJ can't give us a little additional speed."
Jenkins is entering his second season out of the University of Illinois. He caught 90 passes and eight touchdowns in his senior season with the Illini.
The 49ers took Jenkins with the 30th overall pick in 2012, but he was only active for three games and didn't catch a pass.
Jenkins isn't bitter about how his time with the 49ers ended, just ready to turn the page.
"Things happen," Jenkins said. "I'm just looking forward to the opportunity. I'm very excited about working with Alex at quarterback, who I'm very familiar with."
Alex Smith worked with Jenkins that first off-season that the receiver entered the league. That prompted the Chiefs front office to get Smith's take before pulling the trigger on the deal.
"We did, we talked to Alex," Reid said. "Alex was very positive about it."
"I thought A.J. did a great job when he came in," Smith said. "He's a great kid, came in hungry. It was a different situation there last year when he came in. That's a veteran team; a lot of pieces in place. It wasn't his job from the jump. He came in and had to battle for it, and for whatever reason it didn't work out."
After the trade sending Jenkins to Kansas City was made, his former teammate in San Francisco Vernon Davis said in order for him to make it in the league, A.J. needs to take it up a notch.
"I think you know, there are some things that I could work on as far as my physical traits, and also my mental approach."
Jenkins now makes his second stop in the NFL in as many years, and is hoping this is where he can make an impact.
"San Fran drafted me. It's a great team, a great city. But I'm a Chief now, so that's all I'm looking forward to."