INDIANAPOLIS -- This is not an isolated issue that's directed at just one or two players for the Indianapolis Colts. The case of dropped passes has become contagious to the entire group of receivers, tight ends and even the running backs.

Chester Rogers. Marcus Johnson. Zach Pascal. Ryan Grant.

That's only the receivers.

There have been drops -- bad drops -- by tight end Eric Ebron and running backs Nyheim Hines and Marlon Mack.

It's reached the point now where you're no longer surprised when a drop happens. It's almost expected.

The Colts (1-5) have 15 drops this season, according to ESPN Stats & Information. The alarming part is that 13 of those drops, which are an NFL high, have occurred over the past three games. The Colts have a slim margin for error when things are going well. They have proven they have no chance when players can't catch the ball, as they're currently on a four-game losing streak.

"It's been an issue," Colts coach Frank Reich said. "And it's past the point of, 'OK, that was a fluke.'"

An easy excuse for the drops is the Colts are without leading receiver T.Y. Hilton (two games) and tight end Jack Doyle (four games). Though their absence has played a part because some of the players wouldn't be seeing the field as much, it doesn't excuse their inability to catch the ball.

There hasn't been a timetable given on when Hilton or Doyle will return. And the list of injured players at receiver is growing. Johnson was put on injured reserve Monday and Grant is dealing with an ankle injury suffered in Sunday's loss to the New York Jets. On Tuesday, the Colts signed receiver Dontrelle Inman, who has started 30 of 49 games in his career.

"We all know it's a problem -- that we have to keep coaching fundamentals, and we're on them about fundamentals -- and now it's about the fact we'll keep throwing the ball to them in practice, and again," Colts offensive coordinator Nick Sirianni said. "They have to go out and do it. They know that."

The timing of the drops has made things worse.

There was the third-down drop by Johnson that forced the Colts to settle for a field goal in overtime in their loss to Houston in Week 4. There was the Pascal drop that turned into an interception against New England in Week 5. A drop by Mack that was intercepted and returned for a touchdown on Luck's second pass of the game against the Jets. And then Hines dropped what should have been a touchdown in the end zone on a third-down play later in that game.

That's only a few of them.

"I have seen it happen where it's mental, I won't go into specific names in the past of guys who I have played with or coached with, but I have seen players go into a little bit of a ... for lack of a better word ... a funk for a few games," Reich said. "I definitely have seen that happen and I have definitely seen guys get out of the funk and go on to have great years and great careers. So even though three games is way too much, it's not at the point where it's like, 'OK, let's throw in the towel. We got to find a bunch of new guys.' I don’t feel like that at all."

The Colts have their players go through a circuit where they catch 85 balls every practice. They'll continue that, along with having them spend extra time on the Jugs machine after practice because they're not going to magically overhaul their roster. These are the players they have, and they'll be the ones who have to get out of this disastrous funk.

"Our job as coaches is to again teach the fundamentals, but it can't be something we yell at them about," Sirianni said. "We yell at them enough. That can't be one of them. I truly, honestly, believe that, because it can become mental for some of the guys and just like a hitter in baseball, the best way to get out of it is to snag a couple and regain your confidence."