As we wrote earlier, the Boston Red Sox still have much to worry about regarding their starting rotation. Justin Masterson was shelled last night in a loss to the Oakland Athletics. In 11 games this month, the starting rotation is 2-7 with a 6.08 ERA and the Red Sox have fallen to 15-18.

Manager John Farrell said no changes to the rotation were coming "at the present moment" after starter Joe Kelly was charged with six earned runs on four hits and seven walks in Saturday's loss to the Toronto Blue Jays. The Red Sox won their next two games before Masterson's worst outing of the season on Tuesday.

As a result, many are speculating Farrell is mulling changes right now after his comments last night, whether that be promoting a prospect or making a trade. ESPN Insider Buster Olney weighed in on Masterson's current standing in the rotation.

"Masterson is on a one-year deal, meaning that among all of the Boston starters, the Red Sox have the thinnest ties to the right-hander, who has a 6.37 ERA," he wrote. "You have to wonder if Boston will consider shifting Masterson into a relief role and replacing him with one of the prospects working on their Class AAA roster."

One of those prospects includes Eduardo Rodriguez, who the Red Sox acquired from the Orioles last year in a deal that sent reliever Andrew Miller to Baltimore. Rodriguez has made only five starts above Double-A in his career, all of which came this season, and he's 3-1 with a 2.73 ERA, 0.944 WHIP and 29 strikeouts in 29 2/3 innings.

"The decision to fire [pitching coach Juan] Nieves was a shot across the bow to the underachieving starters: Shape up, or pretty soon, the axe will fall on you, too," writes Scott Lauber of the Boston Herald.

"The first move, in all likelihood, would be the promotion of top prospect Eduardo Rodriguez from Triple-A Pawtucket, which could send [Joe] Kelly to the bullpen."

Kelly could be a candidate for the bullpen, but he has a much better as a future as a starter than Masterson. Kelly is 26 years old, Masterson is 30. Kelly is under club control through the 2018 season, Masterson will be a free agent after this year. Kelly averages 96.1 miles per hour on his fastball, Masterson has dipped to an average of 87.1 mph.

The point is, it's inevitable changes are coming to this part of the Red Sox roster. There is no way Boston can sustain themselves and stay competitive in the AL East if their starting pitching continues to maintain a 5.86 ERA (last in MLB).

Sean McAdam of CSNNE.com reported the Red Sox are "moving toward" a DL stint for Masterson because of "general fatigue," which means he may not start on Sunday against the Seattle Mariners. While Steven Wright is said to be a "strong candidate" to take his place, it's probably not the long-term decision.

General manager Ben Cherington has been meticulous in his decision making, so it's unlikely he goes out right away to make a big trade. Look for Rodriguez to get the call in the near future, especially if Farrell decides Masterson won't start on Sunday against the Seattle Mariners. 

UPDATE: Justin Masterson has been placed on the disabled list, according to Craig Calcaterra of NBC Sports' HardballTalk.