ST. LOUIS -- When asked if there were any starts in which he had felt completely comfortable on the mound, Jake Westbrook was hard pressed for an answer. A lower back strain that landed him on the 15-day disabled list Friday became just the latest nagging issue.
"Coming back from [right elbow inflammation in May] and then from the DL was kind of just a feel thing, getting back in the swing of things, and then I guess it's just my body is breaking down on me," Westbrook said. "It's just part of the innings that I've accumulated over my career. It's one of those things.
"It's been tough, been frustrating."
Westbrook said Friday he has been receiving treatment on his lower back for a few weeks, and that the discomfort was at its worst in his start Wednesday in Milwaukee. He is hopeful that with 15 days of rest and some continued treatment he can eliminate the lingering injury and return to full strength.
"It's been tight for a little bit," the veteran said. "It's really more just kind of aggravating. It's another one of the things that I have been just kind of fighting through. Just part of being old, I guess."
The 35-year-old right-hander is 0-4 in his last five starts with a 9.69 ERA, and has struggled since posting a 2.88 ERA before the All-Star break. While he admitted his lower back has been bothering him for a few weeks, Westbrook stopped short of attributing his recent struggles to the issue.
"It's always a grind going out there," Westbrook said. "[I've] kind of been throwing through something the last couple years. It will always be something. But I try to battle through it, and there are no excuses for me. I never make any, I never will. [I] just haven't been pitching very well."
Rookie southpaw Tyler Lyons will take Westbrook's spot in the rotation when the Cardinals host the Reds on Monday.
"When you're sore, it's hard to compete at this level," said manager Mike Matheny. "Jake was trying to fight through it. That is always a tough balance for a player to push whenever they can, but also try and be as good as you can be to get big league hitters out. Give him some time and give Lyons an opportunity."
Chad Thornburg is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.