There's nothing fortunate about an NFL starter being lost to injury for part of the season. Not for the player, and usually not for the team.

When inside linebacker Kiko Alonso was injured in the second game of the year against Dallas, an injury that would require arthroscopic surgery on his previously repaired left knee, the Eagles were forced to stick rookie Jordan Hicks into the fray and hope for the best.

And that's exactly what they got.

Hicks stepped in, played extremely well, and has turned what was a three-man rotation at inside linebacker into what will be a four-man rotation when everyone is healthy, which could be as soon as this Sunday.

"He moved himself up into the conversation," defensive coordinator Bill Davis said. "In the beginning of the year, he wasn't in the conversation other than on special teams and as a backup role while we grew him. But he jumped in and did such a nice job that now he has brought himself into the conversation of [being part] of a main rotation."

Hicks, a third-round pick in the draft, took the field against the Cowboys - and tackled quarterback Tony Romo on the play in which Romo broke his collarbone - and hasn't left since. All three of the other inside linebackers have been inactive because of injuries for at least one game, but Hicks has been the constant, playing 343 of 361 snaps in the five full games since getting his chance.

"If they call your number, you're up. That was just another tackle," Hicks said of the play on Romo. "It's unfortunate he got hurt, but it was just another play and I had to focus on what I had to do going forward. A lot of learning took place after that."

Davis called it a "great challenge to have," but he will have to figure out how to best use and keep happy all four of his inside linebackers now that Alonso is set to play again. That might not have to be addressed this week because DeMeco Ryans, still recovering from a hamstring injury, didn't practice on Wednesday and could still be out on Sunday.

Sooner or later, however, that great challenge will need to be solved. Hicks and Alonso are similar players, both quick and fluid to the ball. Mychal Kendricks is a solid run stuffer in the middle. Ryans is savvy and strong getting off blocks and making plays. Down and distance will make some of the decisions, as will the health of the players. It will matter how Alonso's knee responds, if Ryans can fully recover and if Kendricks, who also missed time with a hamstring injury, can take his normal reps.

"We'll use them as their health allows us to use them," Davis said. "The other factor is when you have those four healthy players, they also have some special teams contributions that they have to do. If somebody just covered a kick and is winded from that, we'll put the other guy in. So, there's a rotation that's kind of fluid during the game [depending] on their health, stamina and special teams involvement."

Beyond that, however, there won't be as many reps available for Ryans, Kendricks and Alonso now that Hicks has joined the rotation. Additionally, while the Eagles started the season by exclusively removing the nose tackle when they went to a fifth defensive back, they have increasingly been taking an inside linebacker off the field for the nickel. Alonso's return could change that because he's considered a plus in pass coverage, but what about Kendricks, who recently received a $29 million contract extension, and Ryans, the respected veteran considered the heart of the defense? Will the rookie really continue to play an expanded role in that company?

"We'll see. Nobody's said anything yet, [no] definitive statement on who's number one or who's going to be doing what or where I'm playing," Hicks said. "Obviously, I want to play. Who's here not to play? At the same time, you want the team to win and you want what's best for the team. Wherever I can fit in, I'll do everything to make that happen."

What has been best for the Eagles for most of this season is having Hicks on the field. He turned Alonso's unfortunate injury into a positive for the coaching staff, which learned it had another player capable of contributing. The downturns at other positions on the field haven't come with similar silver linings. They usually don't, but Hicks is the exception to the rule.

"You're here to make plays. My goal is to earn the respect of this team and the league," Hicks said. "It's a good feeling to see that respect starting to come, but there were a lot of mistakes out there. There's a lot to work on and learn from."

And for Davis, some hard choices to make as he deals with the great challenge of fitting four players into two positions. It might be just three to work in this week, but the problem will arrive sooner or later.

Jordan Hicks did his job when asked and he created the problem. No one is complaining, however. Not yet, anyway.

bford@phillynews.com

@bobfordsports