Steve Keim had looked at all options when David Johnson first got hurt, and that included research on Adrian Peterson. But the push to trade for the veteran running back didn't come until last week, when Keim said he "picked up the phone and it worked out pretty quickly."

The "why" of the deal wasn't complicated.

"I think it's pretty simple," Keim said during his appearance on the "Doug and Wolf" show on Arizona Sports 98.7. "At the end of the day, it made us better. The one thing I am committed to do as the General Manager, and I know Michael (Bidwill) and B.A. (Bruce Arians) is committed to do, we're not going to sit on our hands if we think we can get better.

"It doesn't mean we always make the right decisions. I've certainly made my mistakes here. But the one thing I'm going to do is I'm going to swing. To me, you can never hit a home run if you don't step up to the plate and swing. I owe it to the organization, I owe it to the fan base, and that's the mindset I'm always going to have."

It was interesting to hear Keim, who mentioned at least a couple of times the "mistakes" he has made as a GM. And as good as Peterson was Sunday, he wasn't proclaiming the move the end-all-be-all.

"Hopefully it would add a spark to the offense," was Keim's thought process. "More than anything, I think we created balance."

It also helped morale, Keim said.

"It was about igniting a spark and creating an enthusiasm throughout the building, which was infectious the moment we did it on Tuesday," Keim said.

-- Keim said he thought what was overlooked Sunday was the return of the left side of the offensive line. It was going to be difficult, Keim reiterated, no matter who the running back was with all the injuries. Earl Watford already looks like he'll settle in at right guard, but it was left tackle D.J. Humphries and left guard Alex Boone who showed what impact they could have.

"For the first time this year, we saw five guys up front playing in unison," Keim said. "I thought D.J. was excellent. We've always know he can run block. His ability to roll his hips and finish at the point of attack is something to me that sets him apart from a lot of other tackles. He and Alex on several of those 'deuce' blocks created five- and six-yards of run lanes for Adrian."

Keim also praised the perimeter blocking of the wide receivers that helped Peterson.

-- Keim said there was a lot of discussion with team president Bidwill about Peterson, both on and off the field (including, it stands to reason, the year-long suspension Peterson had after child abuse accusations.) Keim said as with every player, the decision-makers talk through every part of a player, on the field, off the field, in the locker room and in the community. "Both of us were comfortable with that," Keim said.

-- Keim was asked, if he had been GM and not just in the front office in 2007 when the Cards were drafting, if he would have drafted Peterson at No. 5 (The Cards took tackle Levi Brown; Peterson went two picks later.) "You can go back and say that about a lot of different players," Keim said. "I was not the general manager and I've certainly made enough mistakes in the position I'm in now. I'm just trying to take every day, every year and get better at my craft. Hopefully I can put a product on the field that fans can be proud of."

-- About the defense, which allowed a big second half after the Cards built a 31-0 lead before holding on, 38-33: "There is something to be said about momentum," Keim said. "Part of that momentum we created on offense was a good thing. Now we have to figure out why the momentum issues are happening to us on defense."

Keim said the defense played well in spurts, but they need to rally better after giving up a big play. (An aside, the Bucs still converted 50 percent on third downs, which continues to be an issue for the defense.) Keim praised Corey Peters, Frostee Rucker and the work of cornerback Tramon Williams. Keim echoed Arians' thought that Williams should get more playing time. Keim also said safety Antoine Bethea (three picks in three games) doesn't get as much credit as he deserves.

-- Keim said he is confident cornerback Patrick Peterson (quad) will be able to play in London against the Rams.