Brandon Morrow was the Mariners' first round pick, fifth overall, in the 2006 Amateur Entry Draft. He made the team out of Spring Training, after proving that he had something to offer. He quickly became a force in the Mariners' bullpen, mainly as a set-up man to closer JJ Putz. His 4.12 ERA isn't a great number, but as a rookie pitching in 63.1 innings with no prior professional expeirence (3IP in A don't really count), that's not too bad. His other numbers are what made him one of the better relievers. Although Morrow isn't amazing at keeping runners off base, his 56 hits and 50 walks weren't too good (in 63.3IP), but he only had a 0.43 HR/9IP, and a pretty good 9.38K/9IP. His total of 66 K's was a very impressive number. His 3-4 record isn't too bad, but isn't usually the most important stat for a reliever. Now that he has got a full season on his resume, I don't think that it's too important to note his minor league stats. But by looking at his stats on the above link, thanks to The Baseball Cube, for the most part his minor PAC 10, and minor league inning or two or three, his stats have basically continued.
As I mentioned, Morrow was the Mariners' set-up man last season. This year, it was said that he might be competing for the number five job, but now that the Mariners have almost completed a trade for Erik Bedard, he will either be back as a set-up man to Putz, or be a starter with the Rainiers (AAA). I'd say that part of what will determine Morrow's fate will be what Mark Lowe does (Lowe's Spring Training Watch page can be viewed here). Morrow's rookie season shouldn't be considered a fluke, unless he actually does suck. He could be a big factor in the Mariners' bullpen this season. Keep an eye on him.