Whisenhunt spent one season as the Chargers' offensive coordinator under head coach Mike McCoy in 2013 before being hired as head coach of the Tennessee Titans in 2014.
The Chargers' offense struggled in the two seasons since Whisenhunt left. He was fired on Nov. 3 after a 3-20 record as the Titans' coach, including 1-6 last season.
Whisenhunt now returns as the Chargers' new offensive coordinator. The Chargers' running game fell to 30th and 31st the past two seasons.
"The first thing I will say is there were a lot of good things that were done last year offensively," Whisenhunt said, via the team's official website. "But the one thing that stands out is we need to run the football better than we did last year. There is no blame associated there, as there are always factors that are involved. But that is probably the biggest thing we have to do, because then your play action builds off of that, your time of possession increases where you can control the ball and you are in better third down situations.
"All of those things tie in together. Now, it's hard to say you can improve on all of those things significantly in the offseason because there are no pads, but I think you can lay the groundwork for what you are going to do and how you are going to do it. That will carry over into training camp.
"You can do so many things when you are blessed with a quarterback like Philip Rivers. We've got to be able to do things that will complement him, and a good running game is one of those that we have to get better at."
Whisenhunt is counting on 2015 first-rounder Gordon to develop into a solid option. Gordon, 22, rushed for 641 yards on 184 carries and had 33 receptions for 192 yards in 14 games during his rookie season when the Chargers finished 4-12.
"As a young player, you never know how that first year is going to go," Whisenhunt said. "Just like the ball didn't quite bounce the team's way last year, the same went for him. But I can say this. I've talked to Melvin a little bit, and had a chance to meet him briefly. I didn't get a chance to spend much time with him, but with all of the work we did on him as a player coming out, I was very excited about him as a player and what he brings to the table. The same for some of what I saw of him on tape from last season."