The 38-10 thumping of the Lions by the Arizona Cardinals was certainly a surprise. It was certainly not a certainty that the Lions would win, but like all their games this season it should have been close.  Until Sunday night in Phoenix, the biggest loss had been by 10 points to the Vikings at Minnesota.

 So what now?

 After the game coach Jim Schwartz and Matthew Stafford said that the team had not quit. If that’s true, it’s a good sign.

Everything else seems to be in shambles. Much of it is due to injury. Every team has injuries and must get by.

 Here are three things that killed the Lions on Sunday:

1. Matthew Stafford did not have a good day. He threw three interceptions and the Cardinals capitalized on all three. He has to be better. In his defense, other than Calvin Johnson he’s throwing to receivers that he’s not used to at the NFL level. Kris Durham could turn out to be a good NFL wide receiver, but he’s been thrown into the fire. Tight end Brandon Pettigrew’s absence also loomed huge.

2. The defensive line played without the injured Nick Fairley (shoulder) and Corey Williams is gone for the season. Sammie Hill and Ndamukong Suh haven’t worked side by side much this season but they have to do better. Until Sunday the Cardinals’ beat-up offensive line had allowed 51 sacks — nearly four a game. That should have been easy pickings and instead the Lions finished with just one late sack by Suh. 

3. At some point you have to question whether the coaching staff had them prepared. Being out of the playoffs makes it more difficult but the Lions have to be mentally tough. They still have to get up for games and do everything to win. Were they up for the Cardinals challenge? They were hoping to mirror 2010 and win the final four games to go into the offseason on a bit of a good note. It’s going to be tough to win again this season with the Falcons at home on Saturday and the Bears at home on Dec. 30.

Something went horribly wrong this season. It’s tough to pinpoint the reasons why. It’s not on one guy or one group. It’s been a team effort.

(Follow @PaulaPasche on Twitter. Order her new book,  “100 Things Lions Fans Should Know & Do Before They Die’’ here. It’s also available at bookstores.)