A lot has been written this week about the call-up of top prospect Shelby Miller, including a great piece this morning on CardsBlog by Mike Dibiase on the biomechanics of Miller’s delivery. In revisiting Miller’s promotion I want to address the original decision to call Miller up in the first place, its implications for the roster this year and next year, and to briefly touch on Miller’s debut within this context.

A couple of weeks ago Derrick Goold wrote an article on the rules regarding September call-ups, which provided a wealth of knowledge on the various factors teams must consider when deciding who to promote from the minor leagues for the stretch run. Shelby Miller provides a great case study for analyzing how these factors come into play.

First, we must consider the role the player will have on the big league club in September with regards both to developing the player and to increasing the team’s competitiveness. Shelby Miller is currently the most important player in the Cards’ farm system. Efficiently and effectively developing him could produce a future top of the rotation starter for a long time in St. Louis, as he’s only 21 years old.

So how will bringing him up effect his development? Having missed the playoffs, as of September 3rd Memphis’s season was over and Miller’s would have been too had he not been called up. At about 137 innings over 27 starts this year Miller is roughly 5 starts from logging a full big league workload in starts and, assuming he maintained his 5 IP/Start average, that would give him another 25 innings. I am sure the Cards do not want to see him get that high, but when choosing between shutting him down for good or getting him 10-20 innings out of the bullpen against Major League hitters, choosing the latter makes sense.

Second, where does Miller fit into the big league roster? As Goold notes in his article, Mike Matheny has made it clear that there is little value in bringing up a player to sit on the bench: “For us, it’s all about winning right now. Certainly there will be a lot more focus on a player if he can gain all of the knowledge and still be used. We’re not going to get to spend much time with them unless you’re using them when you’re right in the middle of the hunt.” Miller was called up Tuesday and threw two innings Wednesday, so clearly the team intends to use him. Miller had never relieved until Wednesday and took a few hitters to settle in, but he clearly demonstrated that he has the ability to aid the middle relief corps. My guess is that he will see most of his innings early on in low-pressure situations similar to Wednesday’s game against the Mets.

So it seems to make sense to bring up Miller for September from a baseball standpoint, but from a business and roster standpoint there are a few issues to consider. Calling Miller up required the Cards to add him to the 40-man roster and this reality comes with a host of considerations for this year and next.

First, adding Miller to the 40-man roster means that if he returns to the minor leagues next year or in following years the Cards must burn one of his three available option years to do so. Miller did have issues in Triple-A this year, including arriving to spring training underweight and with less velocity, inconsistent command, an over-reliance on his fastball that forced the organization to prohibit him from shaking off his catcher, questions about his makeup and character as a teammate, and, probably most importantly, a soaring HR rate above the already inflated PCL average. For top prospects like Miller, however, actually using all three options—which means that the offseason following the third option he must clear waivers before being sent back to the minors—is rarely a serious issue.

Second, adding Miller to the active roster starts the clock on his MLB service time. Technically this reduces the time until the player becomes eligible for arbitration and eventually free agency, but for September call-ups this is also essentially a non-issue. Miller will be on the active roster for roughly a month. Arbitration kicks in after three years of service time, unless a player falls into the “Super-Two” category, which is a player with 2+ years of service, at least 86 days of service time the year before, and who is in the top 17% of all two year players in service time—typically implying a minimum cutoff of 2 years, 128 days of service.

Translation: the roughly 30 days Miller will spend on the active roster this year will have little or no impact on the Cards’ ability to keep Miller, or on the timetable under which he will remain under team control, unless he does a whole lot of bouncing back and forth between St. Louis and Memphis in the years to come. If that happens then there will be much bigger issues in his development than when he becomes arbitration eligible.

So who is not on the 40-man roster because Miller was called up? All of the useful names on the Memphis roster are already on the 40-man and the same issues for calling up Miller apply to any Double-A prospects that would be called up. As good as Oscar Taveras and Kolten Wong have been, neither of them are as Major League ready as Miller and at this point an extra arm in the pen will get a lot more use than an extra bat off of the bench. Finally, should Chris Carpenter get activated from the 60-day DL the Cards can probably move Rafael Furcal from the 15-day DL to the 60-day DL, clearing a spot for Carpenter, meaning Miller’s call-up has no effect on that situation.

More importantly, adding a player to the 40-man roster means he is there the following season. The only definite subtractions from the current Cards 40-man are Kyle Lohse, Brian Fuentes (who is currently on the Restricted list and so not technically on the 40-man), and Lance Berkman. There are some borderline prospects the Cards could choose to drop in addition to the possibility of non-tendering Kyle McClellan (for a more complete breakdown read this article over at Viva El Birdos), but the bottom line is there is not a whole lot of free space on the Cardinals roster.

The implication? Anyone added to the 40-man this September had better contribute in some capacity at the big league level soon. Is Taveras ready? Is Wong? Maybe. But there’s no reason to risk burning a spot on a guy who will not play now and who may spend all of 2013 getting more seasoning in the minors. Those questions are better left to be reevaluated in spring training, especially given that the Cards currently have plenty of outfielders and second basemen.

So where does Shelby Miller fit in? The Cards inked Jake Westbrook to an extension earlier this year, ensuring that a rotation of Carpenter, Adam Wainwright, Jaime Garcia, and Westbrook will be under contract for next season. Kyle Lohse will likely walk to sign with another club, freeing up a place on the 40-man, about $12M (for those of you who are dubious about Rafael Furcal’s health, the 2013 free agent SS class is unfortunately relatively thin), and one rotation spot.

One rotation spot, to be filled by any one of Joe Kelly, Lance Lynn, Trevor Rosenthal, or Shelby Miller. May the best man win. Of those options, the Cards would clearly prefer Miller, who has the most potential and, frankly, with his $2.875M signing bonus cost the most money. The fact that the Cards chose to call Miller up is in fact a good indication of this preference. The Cards will get a chance to evaluate Miller more in Spring Training, but do not underestimate the importance of seeing him now, at the end of a long season, on a big stage, facing major league hitters in meaningful games.

All of this brings us to Tuesday’s decision to call Miller up and to Wednesday’s debut. With 4 K’s in 7 hitters, should we just give him next year’s rotation spot? I would add a word of caution along with this great optimism.

Miller has an elite fastball, one that it took him about three or four hitters to really display. Whether the Cards brass (correctly) warned him not to try to amp it up too much and hurt himself in his first relief outing, or he just took a few hitters to get comfortable, we should expect that the 93-94MPH fastball we saw at the end of the appearance is the norm, as the scouting reports indicate. Miller is also meant to have elite command and, indeed, his 4 K’s all came on perfectly located fastballs.

Now the word of caution. On the 17 other fastballs Miller threw that did not result in strikeouts, he only hit his spot about 4 times. He went 2-0 on two of the first three hitters and subsequently got away with two mistake fastballs up and in the middle of the plate, shown below. Miller, in fact, repeatedly got away with pitches in the middle of the plate, which he can do to an extent if he pitches at 94, but will be a major issue if the velocity regresses to 91.

Miller also is meant to have a plus, power curveball. This was not the case on Wednesday. Miller got pitcher R.A. Dickey to ground out on a breaking ball and got a called strike on a high curveball. The rest were pretty bad, including the 2-strike offering shown below. His use of the curve to lefties will be especially important, as he demonstrated good command of his change-up, but it does not look like a swing and miss type pitch. If the curve is not a pitch he can consistently throw either to their back foot, on the outside corner back-door, or as a swing and miss pitch down on the zone, then he could end up struggling to consistently get lefties out.

I believe Miller’s velocity will be elite for a starter. I believe his command will also be elite, and do not put too much stock in two innings of work–in his Major League debut, no less. I hope that his curveball will be the plus pitch it has the potential to be. I do worry, however, that if any of those three stipulations are not met he could turn into the Cardinals version of Phil Hughes: a pitcher with dominant minor league stats, a standard three pitch mix that includes plus velocity, but lacking the movement or devastating breaking ball necessary to consistently keep the ball in the yard. Phil Hughes is in the majors to stay, for now, but has bounced back and forth between Triple-A, the bullpen, and the Yankees rotation, burning two of his three option years in the process. By calling up Shelby Miller on Tuesday the Cards made clear that they expect Miller to have much more success than that in the near future.