When Montee Ball went down with a groin injury Sunday against the Cardinals, concern over the Broncos’ run game seemed to increase 10-fold.

The team’s young running back corps had struggled to produce in the first three games, and now their starter, who already missed time because of an appecdectomy during training camp, would miss several more weeks.

Things won’t get any easier Sunday, when the Broncos take on the Jets at MetLife Stadium.

Despite their 1-4 record, the Jets own one of the league’s toughest defenses, especially against the run. It ranks No. 6 in the league in rushing defenses, allowing an average of 83 yards per game. The Broncos’ rushing offense, meanwhile, ranks No. 29, putting up only 79.5 yards per game.

Unlike everyone else, Adam Gase isn’t worried.

The Broncos’ offensive coordinator said Thursday that he is confident in three running backs, Ronnie Hillman, C.J. Anderson and Juwan Thompson.

“I like that group,” Gase said. ” It’s a sharp group and they run hard, and we just got to make sure we’re on it this week because this is probably one of our tougher matchups scheme-wise.”

Hillman, who had 14 carries for 65 yards in the second half of last weekend’s victory against the Cardinals, will make his first start Sunday for the Broncos. Although he’s smaller than Anderson and Thompson, standing 5-foot-11 and weighing 195 pounds, Hillman’s power gives him an edge.

Gase thinks he’s a bit underrated.

“I don’t think Ronnie gets enough credit for the fact that he’ll go up there and meet a guy and he doesn’t get rocked back,” Gase said. “For his size, a lot of guys think they’re just going to run over him. But, for whatever reason, he’s got that power to be able to sustain his blocks.”

The difficulty in facing the Jets, though, comes with coach Rex Ryan’s controlled chaos. There’s no telling what he’ll do.

“You can be in four wides and he’s in base defense. You could be in 12 personnel and he’s in dime. You don’t know what he’s going to do and you’ve got to prepare for a lot of stuff,” Gase said. “He’s been very successful for a long period of time for a reason.”

Having played for Rex’s brother Rob Ryan while in Dallas, DeMarcus Ware is familiar with the “chaos” approach the two use on defense.

“You never know who’s going to be dropping, who’s rushing and it’s like one of those chaotic defenses where, at the end of the dya, you don’t know who’s coming,” Ware said. “You have to sift through the mess.”

Footnotes:Thompson was limited in practice Thursday, but is expected to play Sunday … OL Michael Schofield was still out because of a death in the family and Ball remains out with a groin injury.

Nicki Jhabvala: njhabvala@denverpost.com or at twitter.com/nickijhabvala