Photo by Cheryl Nichols/Nationals News Network

The left-hander has no idea what’s wrong, which leaves an already shaky Nationals rotation a little shakier a few weeks before the All-Star break.

Lannan (2-4) allowed seven runs, six earned, in 4 1/3 innings Sunday while the Nationals proceeded to lose 7-4 in what could have been a winnable game to the Detroit Tigers last night. This is due in part to Lannan’s weakness from the mound.

The Nationals offense produced run support for Lannan early on and were up 4-2 in the fourth, but that wasn’t enough to keep them ahead.

“We need to put this one behind us,” Rodriguez told MLB.com’s Bill Ladson. “Our bullpen has been great and was great again tonight and Walker and Sean [Burnett, who pitched a scoreless eighth inning] gave us a chance to win.”

According to Nats Insider Mark Zuckerman, Lannan continues to string together the worst back-to-back starts of his career. The most puzzling part of the Lannan weak-start debacle is that the lefty who earned the past two opening day starts for Washington due to his consistent and reliable work is no longer proving he’s the same guy.

The problem eating away at Lannan and affecting his game as well as the Nats win-loss count is his trademark sinker that’s been a cornerstone of his success as a pitcher thus far. The problem is the ball’s not sinking.

Could it be injury related? According to Nats Journal’s Adam Kilgore it isn’t. Any elbow soreness forcing Lannan to miss a start this year hasn’t come back.

The most consistent portion of Lannan’s pitching in 2010 is that he’s no longer Mr. Reliable.

“Of course it’s frustrating,” Lannan told Kilgore. “It’s probably the worst I’ve done since I’ve been up here. I’ve just got to keep on battling. I’m not going to stop. I’m not going to just roll over. It’s just a part of my career where I’m getting knocked down and things aren’t going my way. I’ve got to battle through it.”

How about mechanics? Is that the issue? Lannan told Zuckerman that’s not it either.

The fact of the matter is Lannan’s numbers aren’t what they used to be. His ERA is up to 5.45 right now, which is a huge jump when looking at the 3.89 ERA he posted in 64 combined starts between the 2008/2009 seasons.

To keep Lannan as he struggles or not to keep Lannan as he struggles – that is the question. When Craig Stammen was sent down in return for sending Strasburg up, that righty was posting pretty similar numbers to Lannan.

At the moment, there are no plans as to what Manager Jim Riggleman will do mend the rotation. Strasburg continues to produce, Livo remains consistent, and as for the rest of the bunch … it depends on the day.

The Nationals continue interleague play in Detroit at 7:05 EDT. Livan Hernandez (5-3, 2.28) faces Justin Verlander (7-4, 3.56) and the Tigers.