The Cardinals went into Spring Training with a plan to stretch out former closer Trevor Rosenthal, setting him up for a more versatile bullpen role while also giving him an opportunity to win a rotation spot.
The stakes of that rather unusual experiment were raised when Alex Reyes underwent season-ending Tommy John surgery, but just as Rosenthal was about to make his first Grapefruit League start early this month, the right-hander felt lat muscle discomfort. The setback certainly decreased the likelihood that Rosenthal will begin 2017 in St. Louis' rotation -- especially with Michael Wacha appearing to solidify his hold on the No. 5 slot -- but a healthy Rosenthal will get another shot at that first start on Thursday against the Mets.
The job change might never materialize, as was the case a few years back with Albertin Chapman in Cincinnati. But it's an intriguing situation to follow, simply because of the lack of precedent.
The 26-year-old Rosenthal, who last started in 2012 at Double-A Springfield, has worked only in relief in the big leagues while racking up 110 career saves. That total included 45 saves in 2014 and 48 more the next year, when he was a National League All-Star, before losing his job last season.

It's worth noting that just 36 pitchers with at least 100 career saves also have started as many as 30 games, and only seven of those have started 100 or more. In other words, it's rare for one pitcher to get an extended opportunity in both roles. More often than not, those that do begin as starters before switching later in their careers, with Hall of Famers Dennis Eckersley and John Smoltz the two obvious examples.
On the other hand, if a pitcher tastes some early success as a closer, teams tend to be reluctant to try him as a starter. Of the 32 pitchers besides Rosenthal to have at least one season of 30-plus saves by age 25, only Byung-Hyun Kim has gone on to start 15 or more games after that point (more on him later).
A handful of accomplished starters have dabbled at closing games as youngsters, a group that includes Jimmy Key, Kenny Rogers, Curt Schilling, Dave Stewart, David Wells and, more recently, the Cardinals' own Adam Wainwright, as well as Chris Sale. But none had anywhere near Rosenthal's experience in that role before moving into the rotation.
While there aren't many strong comparisons to the path Rosenthal has tried to take this year, here is a look at some of the best, broken down by how smoothly the transition went.
Best-case scenario
Derek Lowe: The right-hander was starting as a rookie with the 1997 Mariners before a trade to Boston. Lowe logged only 13 starts over the next four seasons, and in 2000, he made the American League All-Star team while tying for the AL lead with 42 saves. But things soured in '01, and the Red Sox acquired Ugueth Urbina to replace Lowe as closer. The sinkerballer then shifted to the rotation and led the Majors in starts over the next 10 seasons.

Christopher Wilson: Mostly a starter in the Minors, Wilson pitched in that role six times during his 2005 debut with the Rangers. But over the following four seasons, the lefty made each of his 234 appearances out of the bullpen, saving 51 games over that span. Wilson then won a spot in Texas' rotation in 2010 and pitched exclusively as a starter for his next six seasons -- which may prove to be his last -- making the AL All-Star team for the Rangers in '11 and the Angels in '12.
Mixed results
Kelvim Escobar: The Venezuela native's first attempt at a transition never fully stuck. After saving 14 games down the stretch for the Blue Jays in his debut in 1997, Escobar split each of the next four seasons between the 'pen and the rotation (82 relief appearances, 75 starts), then returned as Toronto's full-time closer in 2002 (38 saves). The second transition went more smoothly, as the righty made 126 starts for the Jays and Angels from '03-07 and posted an adjusted ERA+ of 121 in that span.
Kim: Over his first four seasons with the D-backs, the submarining righty from South Korea pitched almost exclusively out of the bullpen and saved 70 games, including 36 in 2002. He began the next year in the rotation, but after a trade to Boston in May, he returned to the closer role to save 16 games. Still only 25, Kim tried again to become a starter, but over his final four big league seasons (2004-07), he produced only an 86 ERA+ across 102 games (74 starts) for four clubs.
Taking a mulligan
Steve Bedrosian: The righty only started nine of 189 games over his first four seasons and was a part-time closer for the Braves (41 saves). Atlanta then tried him as a starter in 1985, when Bedrosian went 7-15 with a league-average 100 ERA+ over more than 200 innings as a 27-year-old. Traded to the Phillies in the ensuing offseason, Bedrosian returned to relief for good and in '87 saved 40 games to take the NL Cy Young Award.
Goose Gossage: After spending most of his first four seasons in the White Sox bullpen, Gossage saved an AL-best 26 games for the club in 1975 while posting a 1.84 ERA. Chicago nonetheless tried to convert the 24-year-old to the rotation the next year, with disappointing results (9-17, 91 ERA+ in 224 innings). The Sox then traded the righty to the Pirates, and Gossage never started another game as he racked up another 280 saves to earn a spot in the Hall of Fame.

Danny Graves: A closer in college at the University of Miami, Graves made his first 363 big league appearances out of the bullpen and notched 129 saves before starting four games for Cincinnati at the end of the 2002 season. After an ill-fated '03 campaign in the rotation (4-15, 77 ERA+ in 169 innings), Graves returned to his comfort zone in the 'pen.
Bumps in the road
Daniel Bard: The righty doesn't quite belong on this list because he only has five career saves, but he was a highly effective setup man for Boston from 2009-11. The Red Sox then tried to shift the 27-year-old to the rotation, a move that lasted 10 ineffective outings and seemed to derail his career. Bard, now in the Cardinals' organization, hasn't appeared in the Majors since April '13.
Neftali Feliz: As a 22-year-old, Feliz earned the AL Rookie of the Year Award as the Rangers' closer, saving 40 games. He saved 32 more the next year, but a move the rotation in '12 lasted seven starts before Feliz tore his ulnar collateral ligament. Upon returning from Tommy John surgery, Feliz moved back to the bullpen, where he has remained ever since.