Nick Foles was 14-4 under Chip Kelly and 1-5 under Andy Reid as the Eagles' starting quarterback, but the numbers that may be most important when evaluating him this offseason are 10 and 34.

Foles has missed 10 out of a possible 34 starts to injury in his first three NFL seasons. That number could have been higher. Foles fractured a bone in his right hand in the second-to-last game of his rookie year, but he would have missed more time if the season hadn't ended - three weeks total, according to Reid at the time.

He missed just one game after suffering a concussion against the Cowboys in his second start last season. He returned the next week and had one of the greatest half-seasons in Eagles history - completing 67 percent of his passes for 2,269 yards and 21 touchdowns with only two interceptions.

Foles was good in the playoff loss to the Saints, guiding the Eagles to a late fourth-quarter lead that was eventually relinquished. But his first half this season was marred by turnovers and mistakes - despite a 6-2 mark as a starter - and the injury bug bit him again when he suffered a broken collarbone against the Texans.

He sat out the next seven games and will watch backup Mark Sanchez make another start in his place in the season finale Sunday against the New York Giants. It is unclear whether Foles would have played had the Eagles made the postseason, but they obviously thought it was realistic enough that he was kept off season-ending injured reserve.

Foles' injury history does not suggest that he is brittle or lacking in toughness. He played part of his senior season at Westlake (Texas) High with a torn labrum. He missed only two games after dislocating his kneecap during his junior season at Arizona.

He played the second half of the Redskins game his rookie season with a fractured metacarpal bone in his throwing hand. Foles took a beating from Washington in the third game this season, including a blindside shot from nose tackle Chris Baker, and finished despite a bruised left shoulder.

But Foles' propensity for injury should be as disconcerting as his inconsistencies, even if Kelly and the Eagles don't find a better alternative this offseason. It was Kelly who said "durability is the best ability" when he was asked last August about the often-careless Michael Vick.

And Foles hasn't been durable. It may just be bad luck, but Foles' NFL injuries have similarities and partly stem from his holding on to the ball too long and failing to avoid contact.

Against the Redskins two years ago, Foles drove the Eagles down the field just before the half. On first down, he pumped despite having an open Jason Avant in the flat. Sensing pressure, Foles scrambled and was surrounded by three Redskins. But rather than slide, he took on linebacker Perry Riley and was driven to the ground and broke his hand.

In October 2013 against the Cowboys, Foles struggled until he had the Eagles inside the red zone late in the third quarter. He faced third and 9, and when he failed to pull the trigger in the pocket, rolled to his right. He was pursued by two linemen, but rather than throw the ball away, he took a hit, was dragged down by defensive end George Selvie, and suffered a concussion.

Foles' last injury occurred in Houston after he had already been under heavy fire for most of the first quarter. On third and 16, Foles dropped back and managed to skip away from pressure. Four seconds had already elapsed, but he had little time to react and was decked from behind by linebacker Whitney Mercilus.

Kelly said Wednesday that he had yet to evaluate Foles' season as a whole, but he said the team's decision makers would look at every throw before coming to any conclusions. He has only seven games and one quarter of film to watch.

"I don't think we can look back and say this clouds this, this doesn't cloud this," Kelly said. "It doesn't matter how much it clouds or doesn't cloud. That's the reality of it. He got hurt, so we have to make decisions moving forward in terms of what we're going to do."

The questions posed to Kelly had more to do with how Foles' injury gives him fewer games to make a full assessment, but the more tangible question is: "Does the injury - or injuries - factor into the evaluation?"

It would have to. Of the 12 teams in playoff position going into Sunday, nine have quarterbacks who have started every game. Tony Romo missed one game to injury for the Cowboys, and Cam Newton missed two for the Panthers. Only the Cardinals have suffered injuries to their quarterbacks and managed to keep winning.

Last season, 10 of 12 playoff teams had quarterbacks who didn't miss a game. The Eagles and Packers, who were without Aaron Rodgers for seven games, were the only teams to survive casualties to the most important position in football.

Despite losing his quarterback for 11 starts, Kelly has somehow managed to win 19 of 31 games in his first two seasons. He was mostly able to compensate for the losses, but there was little he could do when Matt Barkley was pressed into action and when Sanchez was asked to shoulder the load against some of the better teams in the league.

Kelly likes to say you need two quarterbacks in the NFL, but having one who can stay healthy for all 16 games is of much greater need. Foles, who has one year left on his rookie contract, has yet to prove he can be the one.

Reliability is the best ability.

jmclane@phillynews.com

@Jeff_McLane