I guess it's my turn to weigh in on this.
I have to admit, I've been going back and forth on the issue - at first I liked it, but that's because my first impressions are always shortsighted, and the more I thought about it, the more I started to side with the "send him to the minors" camp. But then, imagining Morrow as a kickass setup guy in front of Putz instead of the probably-horrible Chris Reitsma is so appealing that...well you see where I'm going with this. It's a really really tough decision, and one that I'm glad I don't have to make.
The thing that makes this so difficult, to me, is that I don't think there's a right answer. At least, not one of which we'll ever be aware. Once the team decides to do something with Morrow, they won't be able to go back in time and do the opposite to see how it would've worked out. If they put him on the roster, we'll never know what would've happened had they sent him to the minors, and if they send him to the minors, we'll never know how he would've done as an instant big leaguer. We can speculate, but at no point will one party be able to say "I told you so" to the other, which makes this argument at least partly philosophical. This isn't a trade or a free agent contract or an in-game tactical maneuver where we can analyze the risks and benefits and arrive at one conclusion. It's a discussion that depends almost entirely on your opinion of being aggressive with young players, and as far as that's concerned, no one knows who's right. All 30 Major League organizations take different approaches with their prospects, so it's not like this is something we can't understand as outsider fans, either. At this writing, we just don't know.
I don't need to sit here and enumerate all the pros and cons of either decision, since (A) there are tons, and (B) you've probably read them or thought about them already. Which is good, because that saves me time. We should be able to get by just focusing on the biggest issues at hand, and not worrying about the entire list.
The first thing that stands out to me is that this entire discussion stems from Morrow's performance over 8.1 spring innings. To be fair, it's based more on Morrow's appearance than on his performance - it's his pure stuff that's been the talk of the town, and that means a hell of a lot more than your typical Willie Ballgame-esque ST statistical fluke. It's not like he's getting people out with guile and cunning and 88mph fastballs; he has a powerful arsenal, and that's both repeatable and suggestive of Major League ability. Those who've seen him this month like him not because of what he's done, but because of what they think he could do in Seattle with that fastball/splitter/"slider" combination. Think about what Putz did a year ago with the same repertoire and you can understand where this is coming from. Morrow's flashed some dynamite pitches this spring, and we're beginning to see how far that can take him.
That said, it's the coaching staff (mostly the field manager) that's been leading the charge to get him on the Opening Day roster, and I can't help but appreciate the irony that someone as universally unpopular as Mike Hargrove is the most vocal proponent for one side of the debate. Hargrove makes a lot of bad decisions, and he makes them with considerable confidence, so I have to wonder why no one's really questioning his opinion on Morrow. Hargrove might want the kid's stuff in the bullpen, but Hargrove's leash is so short that his decisions and opinions don't have an eye towards the future, and hence they may not be in the best interests of the organization. Mike Hargrove is not approaching this matter from a big-picture perspective, and so trusting him can be exceedingly dangerous.
Beyond that, as good as Morrow's stuff may look - and it does look good - we still have basically no idea how it currently translates against professional hitters. He's got 3 minor league innings under his belt above Rookie ball, and now 8.1 in ST, where a lot of hitters aren't going up to the plate with the same approach as they'll have a week from now. Raw stuff is great and hugely important, but there are underachievers with good stuff everywhere, so it's not enough by itself. You also need control, command, and a good idea, and right now we don't have much evidence for those other than Hargrove saying "he's been down in the zone," which, whatever. Even if Morrow's location has been great this spring, which isn't necessarily true, location can be flukey (see Felix's fastball, August 2005), and Morrow's got a history of missing his spots, so 8.1 ST innings is hardly convincing. Once again, believing that Morrow's location and approach are currently good enough to survive in the Majors is based more on faith than anything else, and given which people in the organization currently share that belief, one definitely has to wonder.
Of course, it's possible that Morrow is ready for the Majors right now. Mike Hargrove's a bit of a tool, but we can't automatically dismiss his opinions on those grounds, so let's say for a moment that he's right, and that Morrow's capable of being a high-leverage ML reliever right now. Then what?
More than anything else, he'd make the 2007 Mariners better. Much to its surprise, the front office has built a pretty weak bullpen, so finding a Soriano replacement would be totally huge, since I don't think anyone trusts Reitsma to pitch effectively in the role for very long. Although limited, those are critical innings, and Morrow could make this team a few wins better by posting a 2.50-3.00 ERA as a setup guy. (Yeah, I do mean a few, not just one; the 10 runs ~ 1 win rule falls apart in high-leverage situations). If he does that, then the Mariners are in way better position than they looked, and much closer to the top of the division. Getting from 80 to 90 wins is the hardest improvement in baseball, and being able to pick up (say) two or three simply by promoting a prospect makes a huge difference. If Morrow's really and truly ready to pitch in a Major League bullpen, don't underestimate his potential impact. It'd be big.
So after that, then what? Let's say Morrow's one of the better setup guys in the league this year (let's also assume that, if he struggles, he gets sent down to a minor league rotation). What does the team do with him? They drafted him to be a starter, but it's hard to take a guy out of a role where he's had a lot of success; just ask Rafael Soriano or Mark Lowe. There's a great and legitimate feeling that, if the Mariners put Morrow in the bullpen and he does well, he'll never get back out again.
Fortunately, there's this:
"Now, we may have to look at something in the offseason - sending him to a half-season of winter ball, perhaps, and have him re-establish a third or fourth pitch there. But that would depend on how many innings he gets between spring training and the regular season."
Although words don't mean much without actions, having Bavasi weigh in like that helps to allay the fear of pigeonholing (which, come to think of it, is a word that's probably been used more often in the Mariner blogosphere recently than in the rest of the world combined). If nothing else, it shows that the organization still views Morrow as a long-term starter, regardless of what happens with him in 2007. How they'd actually manage that is another issue altogether, but as long as the idea is planted there, it makes me feel better. It'd be hard to pull Morrow out of the bullpen and leave a big gaping hole in the 8th inning, but presumably either (A) Lowe would be back, (B) someone else would take a big step forward in the minors [Kahn?], or (C) the front office would explore the market for help. So that problem would be solved. And even in the event that Morrow doesn't escape - which I honestly think is unlikely - then the worst-case scenario is that we have a neat reliever with a lot of shutdown ability and closer potential. That's a pretty nice consolation prize.
So, yeah. This isn't intended to be an exhaustively-researched academic journal article, but there are most of the main points. If Morrow's ready for the Majors right now, then he could be an important part of the 2007 Mariners, and while putting him in the bullpen would delay his development as a starter (starting and relieving are nothing alike), it wouldn't prevent it altogether. In theory, it would be possible for the Mariners to bake their cake and eat it too, as long as they were smart about it.
That said, we have to consider the possibility that he isn't ready at all, and that Hargrove is just jumping the gun trying to add some fire to a remarkably dull group of relievers. If Morrow makes the roster, struggles with control, and gives up a lot of late-inning runs, it could destroy his confidence and irreversibly alter his outlook as a prospect. A young guy who has difficulty retiring Major League hitters will mess around with anything and everything to try and find that magic fix, and of a sudden you could be left with a different pitcher. If Morrow breaks camp with the roster, the coaching staff will need to monitor him very closely and make sure that he's doing all right, both on the outside and the inside. I do have a lot of trust in Chaves, but the organization as a whole? Not so much.
Look, here's the best I can make of it - there are upsides to both possible decisions, and there are ways to make each of them work out well in the long run. Pretty much any other organization would've optioned Morrow to the minors by now, but the Mariners like what they've got, and they do have their reasons for that. If they set up a long-term plan for him to relieve now and start later, and never deviate from it, and if they're careful with how they handle the guy, then it could work out, and the organization might even be better off because of it. And plus, sweet, we'd get to see Morrow in the Majors. If they don't do that, though, they could really screw things up.
In the end, I just don't know. A big part of me prefers to let him start in AA/AAA for the first half and then call him up to relieve in July if he's doing well, but another part thinks that he could have a big impact right off the bat, and in this decision a few games could mean everything. I suppose what it comes down to is that this is one of those rare situations where people from outside the organization, people with objective viewpoints, probably have the best takes. As a Mariners fan, there're just too many conflicting impressions clouding my judgment. Maybe it's the burden of knowledge, but it could just as easily be that I'm incapable of separating my short-term and long-term desires as a fan.
If nothing else, though, consider what we were talking about in the aftermath of last summer's draft. It's been less than a year and already Brandon Morrow is all but forcing his way onto the Major League roster. What comes out of that may or may not be real good, but the fact itself is highly encouraging. Morrow's doing his part; now the executives in the organization have to do theirs.