There have been 13 players since 2000 who made their first Major League appearance from the bullpen within their team's first 10 games of the season while under the age of 22.
Of those, seven were relievers exclusively in their big league career - Boone Logan, Tim Collins and Huston Street among those.
So, six players who started a game after starting their career the same way that Roberto Osuna and Miguel Castro are expected to start theirs in 14 years isn't exactly a ringing endorsement. But the Blue Jays best case scenario for them may be someone who is in their camp this year.
Those six players? Erasmo Ramirez (21.343 with Seattle in 2012), Jenrry Mejia (20.178 with New York Mets in 2010), Matt Ford (21.359 with Milwaukee in 2003), Oscar Villarreal (21.129 with Arizona in 2003), Miguel Asencio (21.189 with Kansas City in 2002) and Johan Santana (21.021 with Minnesota in 2000). Yes, that Johan Santana who finds himself in Blue Jays camp.
Santana actually only became a full-time starting pitcher in 2004, in his fourth big league season. So, if you have talent, it isn't out of the question for you to become a starting pitcher.
Yes, Santana is by far the outlier in this group and I am not saying that Osuna or Castro will become even close to Santana's peak. Santana was also a different case because he was a Rule 5 pick and Minnesota had no choice but to start on the Opening Day roster, or give him back to his original team.
He also built up into a starter after being in the bullpen, something the Blue Jays saw this year Aaron Sanchez, although Sanchez's clock was started later on in the year.
Of the six players, all of them were primarily starters in the minor leagues, and three of them (Santana, Ford and Asencio) never pitched above A-ball. Again, some similarities to Osuna and Castro.
Of the six, Mejia was probably regarded as the top prospect. He was named the #56 prospect in 2010 by Baseball America and #48 by Baseball Prospectus before making his big league debut. He was seen as a potential starting pitcher. He only started three of his 33 games in his rookie year in the Major Leagues and has become more of a reliever. He finished last season as the Mets closer and has started only 18 of his 106 games in the majors.
He had not pitched above AA before going in the Mets bullpen.
Ramirez started the season in the Seattle bullpen but eventually became a starter but has dealt with injuries since making his debut and has pitched only 47 games (35 starts) in his three seasons.
Ford has not played in the major leagues since his debut season in 2003. Villarreal had only started five of his 258 big league games after being a starter for his entire minor league career. Asencio played parts of three seasons in the big leagues before never making it back to the big leagues.
There is no doubt that Castro and Osuna have been two of the best pitchers for the Blue Jays this spring. The path they are taking to the big leagues is not normal, but there have been talented pitchers to make their debuts around Opening Day despite being young and inexperienced. Jose Fernandez, Michael Pineda, and even Drew Hutchison have made their Major League debuts in April but as starters all at the age of 22 or younger.
Castro, and especially Osuna are not ready to be starters just yet. Osuna has never pitched more than 40 professional innings in a season. Ideally he would be pitching about 80 innings regardless, which would be a pretty good workload from the bullpen. As Andrew Stoeten has written, it makes more sense for those innings to be in the major leagues than to make a few minor league starts.
The service time element of all of this is the least of the worries. Let me make this about a hockey for a brief second. In 2013, the Montreal Canadiens signed P.K. Subban to a two year "bridge" contract for a lot less money than it would have been for a long-term deal. When his contract came up, he had played so well he needed to be paid more than any defenceman in the league.
A lot of people considered this the worst-case scenario for the Canadiens. It was not. Worst-case scenario would have been to sign him long term to huge money and have him bust. For the Blue Jays, it doesn't matter if you have to re-up Osuna or Castro in 2020, 2021 or 2022. If the Blue Jays end up needing to sign Castro or Osuna to a big contract because they perform really well, that's a good problem to have. If either of them become top big league pitchers, the Blue Jays won't complain about having to pay them.
The bigger issue is starting their clock and then having them struggle or not pitching at the big league level. Based on other decisions the Blue Jays have made, I don't feel they will be buried in the bullpen and to this point, they look ready to get big league hitters out.
I don't agree with saying the Blue Jays are throwing away the future for nothing. You don't know what will happen in five or six years. If they get hurt in the minor leagues, it doesn't help anyone either. You have to balance the present and the future and only time will tell whether this was a good decision, a bad one, or one that doesn't end up being a big deal either way.