Washington Nationals’ Joe Ross to undergo Tommy John surgery...

Both GM Mike Rizzo and Washington Nationals’ skipper Dusty Baker were concerned but careful in their wording when they talked Friday about waiting for the results of Joe Ross’s MRI arthrogram on his right elbow.

“I don’t want to speculate on things and don’t want to think the worst,” Baker told reporters, “so we’re preparing for it to be a longer situation.”

“We’re giving him an MRI arthrogram,” Rizzo said.

“We’re going to have it read and we’ll take the next step and make a diagnosis and take it from there once we find out.”

This afternoon in Cincinnati, Baker, as quoted on Twitter by MASN’s Pete Kerzel, announced that Ross will undergo Tommy John surgery this coming Wednesday.

Ross, who had struggled with his mechanics and arm slot all season, after missing time with right shoulder inflammation in 2016, had an obvious drop in velocity on his sinker in his last start, which ended after 3 ¹⁄₃ innings when the Nationals lifted the 24-year-old right-hander with what was described after the game as triceps tenderness.

Ross was placed on the 10-Day DL with a right elbow sprain on Friday while the Nationals waited for the results of the latest tests.

In 13 starts this season, Ross is (5-3) with a 5.01 ERA, 4.98 FIP, 20 walks, 68 Ks, and 16 home runs allowed in 73 2⁄3 IP.

Rizzo said yesterday that they were comfortable with the Nationals’ in-house options if they needed to replace Ross in the rotation, and they would evaluate further when they had the results on Ross.