By Tim Kelly, Sports Talk Philly editor 
The Philadelphia Phillies will be without swingman Mark Leiter Jr. to open the 2018 season. They're lucky not to be losing the 27-year-old for a more extended period of time.
Leiter Jr., who posted a 4.96 ERA in 27 games (11 of which were starts) for the Phillies in 2017, will open the season on the disabled list. According to Jim Salisbury of NBC Sports Philadelphia, Leiter Jr., who had an MRI Monday, has a mild flexor strain, which will sideline him until at least late April.
The flexor strain can be a tough injury for a pitcher, though there are varying degrees of severity to the injury. Cliff Lee, for example, missed the final month plus of the 2014 season with a grade two flexor strain. After resting for the remainder of the season and then spending the offseason preparing to pitch in 2015, Lee ultimately tore his flexor tendon in Spring Training 2015, was unable to pitch through it and elected to walk away from baseball rather than having Tommy John surgery. There's no indication that Leiter Jr.'s injury is as severe as either of Lee's injuries were, specifically the second one.
In the minds of most, Leiter Jr. was a lock to make the Phillies, who are likely to carry an eight-man bullpen, as the long-man. With Leiter Jr. out of the picture to open the season, the Phillies could elect to open the season with just seven relievers, giving them an extra bench spot. This could allow them to carry all three of Roman Quinn, Pedro Florimon and Jesmuel Valentin to open the season.
While the possibility exists that the Phillies will carry just seven relievers until Leiter Jr. is ready to return, the guess here is that Jake Thompson will replace Leiter Jr. in the bullpen as the eighth reliever. Matt Gelb of The Athletic reported Tuesday that the Phillies planned to move Thompson, who was acquired in the July 2015 Cole Hamels trade, to the bullpen. Leiter Jr.'s injury opens up a spot for him on the Opening Day roster.
