Tacoma Rainiers (AAA)
Denny Almonte, OF - Almonte, believe it or not, is a holdover from the ill-fated Bavasi era getting his first crack at AAA pitching. He was a raw, toolsy outfielder coming out of high school when he was drafted in the second round back in 2007. Almonte is still a raw, toolsy outfielder to a large degree. Nothing about his minor league track record suggests a future as a regular, but the fact remains that he is still a 6'2" switch-hitter playing center field that has some 20 home run seasons in his back pocket, as well as a 20 steal season. Almonte's 2012 stats in Jackson aren't very impressive, but there were clear signs of maturity. He walked 52 times, shattering his previous career high (29), while also posting a career low in strikeouts (135, still pretty high, but not as obscene as before). Almonte will log some time in the majors somewhere, if not Seattle, if he finds some sort of success in Tacoma.
Jeremy Bonderman, RHP - Bonderman isn't a prospect, but the Mariners are committed to his comeback bid. Jason Churchill at Prospect Insider is pretty sure multiple pitchers are starting a level lower than they should to make room for Bonderman. The Rainiers also have a couple pitchers starting the season on the DL, most notably Erasmo Ramirez (who won't get sent to AA.) Bonderman's presence cuts into innings that other M's prospects could benefit from, which isn't necessarily a problem, but it suggests a certain commitment level to his comeback. What do the Mariners need to see to stay committed?
Jackson Generals (AA)
Jack Marder, INF - Marder opened up last season as a catcher in High Desert and tore up the league. However, injuries held him to 65 games, most notably a concussion. Marder played all over the diamond in college, and it seems that the presence of other catchers in the system (namely Mike Zunino and John Hicks), plus the concussion, have prompted the Mariners to move Marder elsewhere. My guess is that he plays second base, but the "INF" designation might be pretty true to the word. He could play all over. Marder will enter the top prospect conversation if he hits like he did last year for a full season.
Anthony Fernandez, LHP - Fernandez has too many highly touted arms ahead of him in the minor league system to get much attention. He doesn't have the stuff to become an ace pitcher. However, he is a lefty with an array of pitches he can throw for strikes. He spent the second of last year in Jackson and did plenty well. Expect him to get some more attention once more of "the big four" join Brandon Maurer in the majors. Fernandez isn't on the same level as those guys, but when people start asking who is left in the system after those arms, Fernandez should be among the first names mentioned.
High Desert (A+)
Dan Paolini, OF - I liked Paolini in college as a second baseman that flashed power, but he did against rather low level competition at Siena. His power seemed to translate well, at least in Clinton and the notoriously pitcher-friendly Midwest League. Now Paolini tries his hand in homer-happy High Desert. Paolini needs to move quickly to be a bona fide prospect, which makes this a bit of a make-or-break year, especially because since his calling card needs to be his bat and he's in the most hitter-friendly confines in the M's minor league system.
Jordan Shipers, LHP - I featured Shipers as a sleeper last year in Clinton, and he threw a no-hitter. He's still a bit of a sleeper, and High Desert seems like a very bad match for his skillset, given that he will be young for the league, doesn't generate a ton of ground balls, and doesn't get too many swings and misses. If he finds any sort of success he should get some attention as a legitimate starting pitching prospect.
Gabriel Guerrero, OF - The Clinton team has several hitting prospects worth keeping tabs on. Picking one was difficult. Guerrero has his supporters, and is already known as a bat with one of the highest ceilings in the organization. He has flashed significant power the past few seasons in summer leagues, so this is his first chance to take a crack at a full season. He could struggle, and it's okay if he does. However, Guerrero will generate some serious buzz of his power translates to full season ball, and it just might.
Tyler Pike, LHP - Pike was drafted out of high school last year and got 11 starts in the Arizona rookie league before the season was over. The numbers were impressive and it appears the Mariners felt he was polished enough to handle a full season. A good season in Clinton will assert him as a leader in the next wave of arms behind the "big four."
2013 promises to be a fun season in the Mariners minor leagues. Jack Zduriencik has done a real nice job stocking the farm system with intriguing talent at every level. It is challenging to see where some guys will get enough playing time, which is a good problem to have in a backhanded way. Most of the Mariners top prospects are now in the upper levels of the minors (AA and AAA), which is awesome and exciting, but the lower levels of the minors have intrigue too. The minor league system won't be barren if/when top names in the system right now reach the majors.