But just as everyone was surprised to see Hadnot on the second team at the start of camp, everyone was stunned to see Shelton working behind Anthony Alabi at right tackle.
That's because Shelton has been a starter throughout virtually all of his NFL career (109 starts in 114 games), while Alabi's NFL experience consists of six games in two years and zero starts.
"I can only control what I can control, and that's how hard I play," Shelton said. "I have to eliminate mistakes, and I think I've gotten better every day at camp. I'm confident in my ability, that I'll rise to the top when it's time to play, that I'll be where I'm supposed to be. And if the coaches don't see (me) as a starter, that's where it is. But I have all the confidence in my ability."
A report in the Palm Beach Post this week suggested that Dolphins coaches have told Shelton's agent the reason he's been working with the second team is because of his weight, and that he will be back in the starting lineup once he drops some pounds.
But Shelton, who weighed 338 pounds this week and is listed at 345 in the Dolphins media guide, said that's news to him.
"I don't want to contradict anybody, so that's why I don't want to comment on it," he said about his weight. "But I'm where they want me to be."
Shelton then was asked whether he had been told by his coaches the reason for his not working with the first team.
"No, but nobody has made it seem like it's an impossible feat for me (to get back on the first team)," he said. "I'm just going to keep the right attitude and keep working hard, try to set an example for my teammates and my kids and everybody. If things don't start out the way you want it doesn't mean you can't work out the kinks. That's the attitude I'm taking."
Shelton, who has seen some practice time at left tackle at times during camp, could help his cause with a strong performance in Saturday's preseason opener against Jacksonville.
But he doesn't buy the notion that there's more pressure on this game because of his current status.
"The pressure is always on, especially when they bring in young guys, new coaching staff, youth movement," Shelton said. "They're going to give the young guys the chance just as much as the older guys, so you have to be that much better."
Shelton has been a serviceable starter in the NFL, but the truth is he hasn't been a top-notch offensive lineman the way his status as the 21st overall selection in 1999 might suggest.
Alabi, meanwhile, is a fifth-round pick who needs some refining but just might have more upside than Shelton. And that might be why he's getting a long look with the first unit this summer.
In the end, this battle will be one to watch. Even if he doesn't start, Shelton will give the Dolphins some quality depth at both tackle spots.
Make no mistake, though, that's not what Shelton is looking for. He's always been a starter, and he wants to continue being one.