Trevor Rosenthal could be the next Derek Lowe

Trevor Rosenthal finishes off games with a fastball that reaches 100 miles per hour. Derek Lowe's fastball regularly sat at the same speed as a Rosenthal changeup. They do not appear to be players that make for an easy comparison. In this case, the person making the comparison has made a living getting owners to connect dots and once compared Barry Zito to Steve Carlton. Everything Scott Boras says, especially when it comes to his clients, like Rosenthal, should be taken with a grain of salt, but Boras is telling Rosenthal the same thing he told Lowe.

"Derek was a really, really good closer and he always wanted to start and I told him the same thing I told Trevor: You would be very successful as a starter," Boras said. "It's your call. You have to work it out with your team. He does not want to leave his teammates in a lurch."

The article linked above (which I recommend reading) from Stan McNeal at Fox Sports Midwest discusses Rosenthal's positive outlook and demeanor as a closer, but does mention that Rosenthal would like to start at some point. Derek Lowe, like Rosenthal, came to the majors after starting in the minors. Also, like Rosenthal, he was very successful in a bullpen role and remained there for some time. Recent memories may cloud perceptions of Lowe, but he was one of the best relievers in the majors. Here are the top relievers from 1997-2001 in terms of fWAR (from Fangraphs Leaderboards)

Derek Lowe was great as a reliever to start his career, but beginning in 2002, he got his chance to start and excelled.

Lowe had little problems with durability, averaging more than 200 innings per season over his next five and averaging between 3 and four wins per seasons. He made more than 32 starts every year for the next ten seasons. Rosenthal hopes to one day make the same transition. Not every reliever can automatically become a starter. Lord knows, the Cardinals have tried. Rosenthal has the stuff and build that could lead to a greater role.

As Boras notes, "There is a financial component to this." In the long haul, relievers are paid much less than starters. However, that is not quite as true in arbitration if the reliever is a closer like Rosenthal. He stands to lose very little over the next four years of team control if he can continue to close out games for the Cardinals. Jason Motte made under $2 million in his first shot at arbitration prior to 2012 when he had little in-season experience closing. After closing out games for all of 2012, Motte was due a big raise and signed a 2-year $12 million deal. For a player like Rosenthal, his comparison will be to Craig Kimbrel, who in his first year of arbitration, demanded $9 million before "settling" for a 4-year $42 million contract. As a closer, Rosenthal will get paid in arbitration, but he and his agent know that when it comes to free agency, the starters get substantially larger paychecks.

Rosenthal is not without his flaws, as he saw his BB% climb from 6.4% in 2013 to 13.6% in 2014. John Mozeliak noted the same.

While Mozeliak admits that Rosenthal possesses the talent to start, his high walks total last season showed he still has work to do. "One thing he struggled with at times was command," Mozeliak said. "When you start to say you're going to start, you have to be more efficient."

That leaves the question of whether or not Rosenthal can be effective as a starter. He has a strong backer in Joe Schwarz, who wrote this (which I also recommend and has a lot of information on Rosenthal's skills translating into a starter role) before 2014 started:

He has the desire, repertoire, and stamina for the role. He may never become an elite starting pitcher, but does he really have to be? For how awesome he was last season, he accounted for 2.2 fWAR. The likelihood of him getting to that number on a consistent basis isn't all that great-as shown by his ZiPS projection of 1.6 for 2014. A starting pitcher's WAR can reach a level in one season that takes relievers multiple seasons to reach. He could have an average to above-average 2014 as a starter and still have a higher WAR than he did in 2013.

Rosenthal came up as a starter and was moved to relief because of need, not because there were those who questioned his ability to start. Prior to 2013, Keith Law ranked Rosenthal in his Top 100 prospects and believed his future was as a starter.

Rosenthal has two great attributes to keep him in the rotation -- that big fastball, more 92-97 when he's starting, and the athleticism that allows him to repeat his delivery even with some effort and to locate his fastball around the zone. His arm is so quick that everything he throws is hard, sometimes compromising break or movement. His slider touched 92 once in the majors last year, and even at its usual 88-90, it's more like a big cutter than a true slider; his changeup is closer to a BP fastball; his curve has the strongest definition, right around 80-81 mph with downward break.

Rosenthal's immediate future is as the Cardinals' closer, and he needs to show in 2015 that he can still excel in that role after struggling some in 2014. Making the transition to starter is a difficult one, but most relievers find themselves in the bullpen because they have proven they cannot start. Rosenthal has yet to do so. He could very well follow the path of Derek Lowe. The Cardinals retain four more years of control on their current closer, and the makeup of the bullpen and the rotation will likely change significantly during that time. Rosenthal deserves a shot at the rotation at some point in time. Hopefully he gets that opportunity with the Cardinals.