When the Texans take the field Friday for the first of two-a-day practices, coach Gary Kubiak has a couple of concerns he knows must be addressed during training camp and preseason.

The first concern involves getting all of the injured players healthy. Kubiak’s philosophy is to bring along injured players slowly, even if they’re 100 percent, such as inside linebacker Brian Cushing.

Kubiak wants to make sure the players who have recovered from surgery are ready for the regular-season opener at San Diego.

Cushing (knee), offensive tackle Derek Newton (patellar tendon), free safety Ed Reed (hip), receiver DeVier Posey (Achilles tendon), cornerback Brice McCain (foot) and defensive end Tim Jamison (Achilles tendon) won’t be rushed back.

The second concern falls in the same category. The Texans have to find quality depth, and they’re going to be counting on some young players who are still developing and have yet to prove themselves on a consistent basis.

They have to replace all the players lost after the last two seasons, including starters like outside linebacker Connor Barwin, fullback James Casey and safety Glover Quin this year.

Other starters who have to be replaced are receiver Kevin Walter and nose tackle Shaun Cody.

Backups could be big

You realize why depth is such an issue when you consider other players lost after the 2011 season, including defensive end Mario Williams, inside linebacker DeMeco Ryans, tight end Joel Dreessen, receiver Jacoby Jones, offensive tackle Eric Winston and guard Mike Brisiel.

And we’re not even including kickers and punters.

That’s a lot of talent no longer there.

With depth in mind, let’s look at five players for fans to keep an eye on during camp and preseason.

Let’s start with running back Ben Tate. The coaches don’t want Arian Foster setting another career high in carries, as he did last season with 351. They need Tate to stay healthy, unlike last season when he ran only 65 times for 279 yards and ranked third on the team in rushing.