Byrnes originally hurt his hamstring while running sprints with teammate Chris Young just before the start of Spring Training.
"We were having some fun -- we were pushing each other getting ready for Spring Training," Byrnes said when asked if the pair were racing. "It was just a little tweak that stayed there and stayed there, and I think what happened is I overcompensated on the other side."
That left Byrnes with pain in both hamstrings, and he continued to insist that he could play. Each day, he would arrive at the ballpark six hours before game time to receive treatment in the training room.
"Each day I came to the ballpark, it was a mystery until I got out there," he said. "It's hard to explain, unless you've ever dealt with hamstring issues."
Byrnes has been mired in a slump at the plate over the last three weeks, and it became apparent to manager Bob Melvin and general manager Josh Byrnes that something had to be done.
The team discussed going on the disabled list with Byrnes a few weeks ago, but at that time he felt his hamstrings were getting better and no move was made.
"We've been going this route for quite a while," Melvin said. "He's not 100 percent, in my opinion, not even close, his hamstrings are bothering him, and he needs all his weapons to be Eric Byrnes -- and we need him to be 100 percent. We need him to play a certain way, and he's just not able to do it."
Byrnes, who stole 50 bases last year, has just four in seven attempts this year. He freely admits that the leg issues have hampered him on the bases, but declined to blame them for his .219 average at the plate.
"Look, I couldn't run the same way, there's no doubt about that, I knew that," Byrnes said. "I'm not going to blame my hitting slump on my legs; I won't do it. Did it help? No, it definitely didn't help. That's something that I've gone through before. Look, no one is immune to that in here. You're starting to see that, even some of these young guys are starting to struggle. It's the reality of baseball. I mean, I went 9-for-95 before. I've dealt with things like this before.
"On the flip side, I like to think that when I get hot I also get as hot as anyone in baseball too. Like it or not, that's the type of player I've been."
Byrnes will leave the team for a few days to fly to the Bay Area to see Nick Athens, a chiropractor who has worked with athletes such as Tom Brady, Ronnie Lott and Joe Montana. He will return to the team over the weekend, and travel with them on the upcoming three-city, 10-game road trip.
"Hopefully, in 15 days, I'm ready to go and help us down the stretch," he said. "I think the most important thing is obviously getting healthy and being strong for the second half of the season."
Jeff Salazar started in place of Byrnes on Tuesday, but Melvin said Chris Burke would see time there, as well, particularly against left-handers.
"I'm going to play Burke out there against some left-handers, give him a chance to get some consistent at-bats. We haven't been able to do that for him," Melvin said. "I think he's swinging the bat a little better, so I'll give him a chance to get out there and get a few more at-bats."