And a veteran replacement anywhere near his caliber doesn't appear on the horizon.
An MRI indicated Keller tore three ligaments and potentially also suffered nerve damage —a potentially career-threatening injury — in Houston on Saturday night, The Miami Herald has learned. The team had not made a roster move as of Sunday afternoon, but it's a formality that he will be put on a year-ending injured list.
Without Keller, the Dolphins have no real veteran presence at the position. While the team has drafted a tight end in each of the past three seasons, Dion Sims, Charles Clay and Michael Egnew have not yet established themselves as dependable deep-seam threats.
"We have other guys who have caught the ball down the middle," Dolphins coach Joe Philbin said late Saturday. "We have some big targets. Egnew's a big man. Dion Sims is a big man. Clay has caught the ball down the middle before. We'll adjust."
The Dolphins placed some preliminary calls for a potential replacement Sunday, but the feeling by many around the league is they will probably go largely with what they have at the position.
If they do go the free agent route, possibilities include Travis Beckum, Daniel Graham, Todd Heap and David Thomas. Former Giants tight end Kevin Boss has not been cleared medically after sustaining a concussion last year, and Beckum is still a couple of weeks from being healthy enough to play.
But more likely, it will fall on Egnew, Clay and Sims to step up.
"There is going to be a lot of pressure," Egnew said. "There's always a lot of pressure. Fortunately, we're coached well. I think we can naturally fall right into it."
Added Clay: "It's something I've been working real hard at and getting better at. If my number is called, then I have no choice but be ready."
But Saturday night's 24-17 loss to Houston illustrated just how steep the drop-off is from Keller, who when healthy is a top-15 tight end.
Egnew had one catch for 14 yards. Clay and Sims didn't touch the ball all night. Making matters worse, all three were flagged for penalties in the game's first 18 minutes.
Sims has shown encouraging signs this summer, but he's still a raw rookie. The Dolphins have a pretty good idea of what Clay can do; he's now in his third season.
But neither has the draft pedigree of Egnew, a third-round pick from 2012 who was named by Philbin as one of the team's most improved players during training camp.
Keller was injured while trying to catch a pass in the flat. Texans rookie D.J. Swearinger hit him in the knee with his helmet, a legal play that ignited a national conversation Sunday. Swearinger told reporters after the game he went low because if he had hit Keller high, he would have risked a fine.
"They made several adjustments to cut blocks," offensive tackle Tyson Clabo said. "In my opinion, this is a similar situation. If they can protect defenders from low blocks, they should protect offensive player from that type of hit."
Added former University of Miami tight end Kellen Winslow Jr. on Twitter: "The NFL needs to protect defenseless receivers from low hits. To me that is way more important than helmet to helmet."
For the most part, however, Dolphins players used social media Sunday to wish Keller well. He has become a well-liked teammate in his short time in Miami, and some believe he will be as big of a loss in the locker room as on the playing field.
"My thoughts and prayers are with @DUSTINKELLER81 today," wrote guard Richie Incognito. "Great teammate and great ball player. I hope he has a speedy recovery."
"Josh Samuda, who has surrendered sacks in each of the last two games as the Dolphins' starting right guard, lashed out at critics of his play on Twitter early Sunday morning. Samuda later deleted the tweets.
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