D.J. Humphries is an optimist at heart, so the Cardinals' left tackle bought in to the Air Raid the moment Kliff Kingsbury was hired.

It's a good thing his coach is more of a realist.

Kingsbury was smart enough to see his pass-happy style wasn't working early in his NFL tenure, and the shift to more balanced football was one of the most significant developments of the 2019 season.

The decision by Kingsbury to change his scheme midseason garnered respect from his players for two reasons:

1) The more run-focused attack played to the team's strengths.

2) Kingsbury proved he was not too stubborn to ditch a fruitless idea.

"A lot of people – especially coaches in general – like to make it feel like, 'I know it all (and) I can't let anyone know I don't,'" Humphries said.

Kingsbury was never that.

Even during the peak of Air Raid-mania in the offseason and training camp, Kingsbury always said the offense would evolve based on personnel, and there was no better example than the ascension of Maxx Williams.

The veteran tight end signed with little fanfare in May, and not only made the team, but barged his way into a major role. Williams finished with the top offensive grade on the team in 2019, per Pro Football Focus, contributing both as a receiver and a blocker.

"I said it from the start: Our roles were going to be whatever we wanted it to be," said Williams, who signed a two-year contract extension in November. "We were going to come here every day and work. All of us tight ends who were here this year, that's all we wanted to do, was come here and play. We got our chance, and did whatever we could to help."

While Kingsbury may not have run four- and five-wide formations as often as predicted, his creativity was as advertised. There seemed to be at least one or two gadget plays per game that caught the defense off-guard – from flea-flickers to wide receiver passes to inventive use of motions and shifts.

Kingsbury also had a knack for game-planning, which contributed to a stark turnaround in offensive efficiency in 2019.

"There were weeks we implemented a brand-new offense, basically, from week to week sometimes, just because what we did the week before wouldn't necessarily work the next week," center A.Q. Shipley said. "They did a great job game-planning all year long, and we did a solid job adapting."

In his end-of-the-season press conference, Kingsbury noted the healthy amount of cap space the Cardinals will have in free agency. If the offensive personnel gets upgraded, maybe the Air Raid will return in 2020.

"I'm sure it could," Shipley said. "They'll evaluate it. They're going to constantly evaluate what we have and constantly evaluate what we're good at. That's the sign of a good coach."

Whichever way Kingsbury takes things moving forward, the players are excited to be a part of it.

"Coach adapted throughout the whole year, no matter what he wanted to do, and it worked for us," Williams said. "Obviously our offense grew together. Now we just have to bring the momentum into the offseason and get ready to go next year."