With great mercy and foresight, the Toronto Blue Jays optioned Brad Mills back down the Triple-A Las Vegas, tipping Luis Perez to start in Mills’ place on Saturday. The only mystery surronding this move is how on Earth Brad Mills managed such an impressive line in the hitter’s delight that is the PCL. Sometimes you can make tip-toeing through a minefield work for a little while.

The corresponding move finds the Jays promoting 24-year old pitcher Joel Carreno with the intention of moving him to the bullpen. Manager John Farrell suggests the team will bring Carreno along slowly due to a lack of familiarity with pitching in relief, a role he filled in Spring Training but not since that time.

Joel Carreno is an interesting prospect in that he wasn’t much of a “prospect” before this season. His numbers at A and Rookie ball were always good but he was considered too old for the level. His numbers with high-A in 2010 were very strong (in a pitcher’s league) but he didn’t get a lot of attention on Jays system rankings because of his age (and the whole pitcher’s league thing.)

The team finally moved Carreno to New Hampshire of the Eastern League where he continued compiling strikeouts against the strong talent pool. The right-hander uses his fastball/slider combination to K more than 10 batters per 9 innings, offsetting his slightly scary 12% walk rate.

Jared McDonald of Jays Journal provides a very comprehensive scouting report here, citing Carreno’s lack of effective change up as a potential stumbling block for his development as a starting pitcher.

Bringing us to today and…the future. Does Joel Carreno profile as a potential closer?

His fastball doesn’t touch the upper 90s but his ability to miss bats at the minor league level bodes well. His advanced age suggests the team might give Carreno every opportunity to prove he can hack it in the bullpen right away.

Could Jonathon Papelbon be a reasonable comparison to Carreno? Back in 2004, Papelbon struck out 153 hitters in 129 innings at age 23, compared to 43 walks. Carreno managed 152 strikeouts in 134 innings with 68 walks in that very same Florida State League. Both starters at slightly advanced ages, both players with strong fastball/slider combinations. The Red Sox closer added a splitter before the 2005 season which really took his game to a higher level.

The thought of moving a starter to the bullpen is generally not a good one, especially if the player has not proven they cannot hack it in the rotation where they provide so much more value. The question becomes: do the Jays project Carreno as a big league starter?

Addressing a hole like the back of the Jays bullpen with an in-house option is a much more attractive option than paying for saves on the open market. Even a current setup pitcher (like David Roberston) with “Closer Potential” costs a lot more than converting an effective-but-limited starter.

The Jays aren’t going to thrust Carreno into a high-leverage situation right away but expect many peeled eyeballs when he takes the mound against a legit left-handed batter for the first time. A few more miles per hour on his fastball when he isn’t stretching out for 6-7 innings could go a long way in shaping the future of the Jays ‘pen.