 On April 8 , 2015 , Nathan was placed on the 15 @-@ day disabled list due to a strained right elbow . During a rehab start with the Toledo Mud Hens on April 22 , Nathan re @-@ injured his elbow after throwing only 10 pitches . The same night , Nathan underwent MRIs , which tested positive revealing tears in his ulnar collateral ligament of the elbow and his pronator teres muscle , and would undergo Tommy John surgery , ending Nathan 's 2015 season . Sources projected that this surgery could end Nathan 's career , but he was not planning to retire yet . 
 On April 8 , 2015 , Nathan was placed on the 15 @-@ day disabled list due to a strained right elbow . During a rehab start with the Toledo Mud Hens on April 22 , Nathan <a href='uninflect' title='1'><mark>re</mark></a> @-@ injured his elbow after throwing only 10 pitches . The same night , Nathan<a href='been_done' title='2'><mark></mark></a> underwent MRIs , which tested positive revealing tears in his ulnar collateral ligament of the elbow and his pronator teres muscle , and would undergo Tommy John surgery , ending Nathan <a href='null_genetive' title='3'><mark>'s</mark></a>2015 season . Sources projected that this surgery could end Nathan <a href='null_genetive' title='4'><mark>'s</mark></a>career , but he was not planning to retire yet . 
On April 8 , 2015 , Nathan was placed on the 15 @-@ day disabled list due to a strained rite elbow . During a rehab start with the Toledo Mud Hens on April 22 , Nathan red @-@ injured his elbow after throwin only 10 pitches . The same night , Nathan done underwent MRIs , which tested positive revealing tears in his ulnar collateral ligament of the elbow and his pronator teres muscle , and would undergo Tommy John surgery , ending Nathan  2015 season . Sources projected that this surgery could end Nathan  career , but he was not planning to retire yet .