Here at SeattleClubhouse, our primary goal is to get information on Mariners players to the fans that want the knowledge. Looking beyond the numbers and using input from scouts and other baseball personnel and putting that together with my own input, I am going to give you a brief rundown on quite a few names in the Seattle organization that are worth tracking. Keep in mind that while the top five or seven players are fairly secure in their rankings, the rest of these players' positions in the rankings will be very fluid going forward.
Here now is part one of our initial ranking of the 50 best prospects in the Seattle Mariners organization.
50. Kevin Rivers 23-years-old, outfielder, Low-A Clinton
Rivers entered the organization as an undrafted free agent following his college career at Division-II Franklin Pierce University. Undrafted free agents typically are roster-filler, but Rivers' 2010 season definitely was worth noticing: .332/.466/.556 with 60 BB in 71 games for Everett.
Although 2011 in Clinton wasn't great, his .254/.338/.413 line with 34 BB in 86 games and a great stretch that won him Midwest League Player of the Week honors suggest that there is something worth keeping an eye on in his bat.
Everett Manager Scott Steinmann said that Rivers, "really took to the adjustments we made", while producing there in 2010. His build (6-foot-2, 210 pounds) and left-handed stroke have overcome his lack of ideal athleticism to this point, but he's probably best suited for left field, first base or DH duties as he advances. That said, he doesn't have any plus tools at this point at the plate either...which means the bat will have to turn it up a tick or two if he is to become a serious prospect.
49. Nate Tenbrink 24-years-old, third base, Double-A Jackson
Tenbrink was a 7th round selection in the 2008 draft and got off to a slow start to his professional career, hitting just .198 for Everett that season. But a very good 2009 in Clinton followed by some great numbers across two levels in 2010 put him on the map for prospect watchers.
He struggled with his batting average this season in his return to Double-A, though some of that could have been bad luck, but the strikeouts (60 in 254 PA) were more of an issue than in the past. His power did increase, however, and his plate discipline and walk rate--one of his better tools--were still very present, allowing him to produce to the tune of .218/.337/.403.
After seeing regular playing time in the outfield in 2010, The Kansas State alumni and left-handed hitter once again played mostly third base in 2011 before he was placed on the 7-day DL following the June 27th game and didn't appear in a game the rest of the season. The diagnosis ended up being a stress fracture in his right elbow.
When healthy, Tenbrink has a nice level swing path with average bat speed, plus plate discipline and pitch recognition and at least 50-55 speed. He has struggled defensively as a third baseman to this point in his minor league career, and the position is suddenly much more flush with talent for the M's, so I wouldn't be surprised to see Tenbrink start seeing a lot more outfield time in 2012, when he will likely repeat with Jackson.
48. Tony Butler 23-years-old, starting pitcher, Low-A Clinton
Butler was a highly touted prospect for the Mariners in the past, ranking as high as #4 on Baseball America's preseason farm review back in 2007. As a former 3rd round pick out of Oak Creek high school in Wisconsin, Butler had shown promise early in his career. Injuries, trades and struggles followed, but he is working himself back into form.
Butler's two biggest reasons for being one to watch are the fact that he is 6-foot-7 and that he throws left-handed. His repertoire includes a fastball, curve ball and change-up. His fastball is typically in the 88-91 range these days, but he throws a few different versions now--cutting it or sinking it when needed, and his two-seamer has good downward plane on it. Butler also throws a big curve, a "1-7" variety breaker, in the high 70s that is his out pitch. He has decent separation on his change.
This second trip through the Mariners system is going about the same as his first, but he is now five years older. During his time in Clinton this season Butler was hurt by a .325 baBIP, so his 3.26 ERA, 1.38 WHIP and .249 oAVG could be even better. He'll be pushed to at least High-A next season and will have to continue to show improvements. He may be a reliever down the road, but the advancements he has made in his mechanics and his control suggest that starting isn't quite out of the question yet.
47. Dennis Raben 24-years-old, first base/designated hitter, High-A High Desert
Speaking of injuries, meet Dennis Raben. He was drafted as one of the most promising power bats in the 2008 draft when the M's tabbed the big left-handed hitting outfielder/first baseman with the 20th selection of the second round, but ever since his college days, Raben has just had a hard time staying on the field.
When he has been healthy, Raben has hit: .306/.382/.581 with 52 doubles, 43 home runs and 77 walks in his 185 minor league games. Although he has always had a pretty good arm, he has only seen 32 games in the outfield thanks to the microfracture knee surgeries and other injuries and is likely a DH/1B only guy now. While his numbers in the Cal League this year did balloon a bit from his home park, the now 24-year-old Raben did still produce an .826 OPS on the road this year.
Some evaluators threw around 70s for his power before the draft, and he probably still has that ability--to all fields, with a swing that generates very good natural loft and backspin--but having missed parts of the last two seasons and all of 2009, Raben has fallen into some bad habits and his once above-average plate discipline has declined a bit. His swing is long too, which leads to more strikeouts than someone with his eye should accumulate. He has to find a way to stay healthy and put his power and hitting skills on display for 120-plus games if he wants to advance before his time runs out for the Mariners.
46. Tyler Burgoon 22-years-old, relief pitcher, Low-A Clinton
Burgoon was drafted by the Mariners in the 10th round out of the University of Michigan in 2010. Just 5-foot-10 and 160 pounds, Burgoon is a bit undersized for a pitcher, but he does have a big arm. He pitched briefly for Everett in 2010 with mixed results (4.40 ERA, 15 Ks in 14 1/3 IP), but broke out a bit this season: 2.30 ERA, 1.12 WHIP, 66 strikeouts and only 15 walks in 62 2/3 relief innings covering 42 games.
He doesn't fit your typical bullpen power arm profile because of his size, but Tyler can still rush his fastball up there in the 91-94 range with some late arm side run. He also has a good hard slider that has flashed as a plus pitch at times in the 83-85 range. The big key for him is command, and he has done a consistently great job of that as a pro with an easily repeatable, compact delivery.
Don't let his "low" ranking here fool you: he can be a fast mover and legitimate big league contributor for the Mariners in short order.
That's it for our first five. Check back every Friday as we reveal five more players in our countdown to the top prospects in the Mariners system.