This year's Top 100 Prospects lists feature a number of promising young starting pitchers, including the Dodgers' Jose DeLeon, Colorado's Jon Gray, the Mets' Steven Matz, Oakland's Sean Manaea, and Cincinnati's Amir Garrett. In addition to the accolades they have received from Baseball America, Baseball Prospectus, MLB.com, and faketeams.com, these five prospects have something interesting in common.
All are older than Seattle's Taijuan Walker.
Walker, 23, made his Major-League debut late in 2013. Since then he has started 37 games for the Mariners, 29 of them in 2015, when he became a fixture in Seattle's rotation. Last season Gray made 9 starts for Colorado, and Matz started 6 games for the Mets. De Leon and Manaea have yet to pitch above Double-A. Garrett spent all of 2015 in the High-A Florida State League.
Fantasy players who deem Walker a disappointment--last season he "boasted" a 5.03 ERA as late as July 26 and probably ended up on many re-draft waiver wires--might want to reconsider in light of his age and pattern of development through the minor leagues. In 2015 Walker finished 11-8 with a 4.56 ERA, 8th-worst in the American League among qualified starters. Given Walker's youth and relative inexperience, however, there were a number of silver linings in this performance, and they are not difficult to find.
First, as his late-July and final ERAs suggest, Walker appears to have gotten better and stronger late in the season. Lowering his ERA from 5.03 to 4.56 in two months' time might not seem like a Herculean task, but it did require several dominant outings, including a complete-game, one-hitter with 11 strikeouts at Minnesota on the final day of July. He made a combined eight starts in August and September; six of those were statistical "quality starts."
Second, Walker has his BB/9 ratio moving in the right direction. After issuing more than three walks per nine innings at every minor-league level in which he made more than one appearance between 2010 and 2014, Walker posted an impressive 2.12 BB/9 ratio in 2015, which suggests that his control is improving, and he's only now learning how to throw quality strikes.
Finally, and perhaps most encouraging of all, Walker's pattern of development through the minor leagues suggests that 2015 might be nothing more than a hiccup on his way to a major breakthrough in 2016. After dominating the Low-A Midwest League as an 18-year-old in 2011--no small feat, by the way--Walker skipped a level and spent all of 2012 with the Double-A Jackson Generals, where he made 25 starts and struggled with both control and command. His ERA ballooned from 2.89 to 4.69, and his K/9 ratio fell from 10.52 to 8.38. The Mariners wisely sent him back to Double-A in 2013, and he responded with an impressive 2.46 ERA and 10.29 K/9 ratio in 14 starts before earning a promotion to Triple-A Tacoma and eventually to the Majors.
In short, Walker's first full season in Seattle (2015: 29 GS, 4.56 ERA, 8.33 K/9) bore a striking resemblance to his first full season at Double-A Jackson (2012: 25 GS, 4.69 ERA, 8.38 K/9), with the encouraging exception of his BB/9 ratio (3.55 in 2012; 2.12 in 2015).
Alas, the longball plagued Walker in 2015 to a much greater degree than it ever had in the minors. He surrendered 25 home runs, tied for 9th-worst in the AL. Oddly enough, this does not appear to have been a control-related problem. On the majority of those 25 homers, Walker actually hit the catcher's target, or very close to it. Only 6 of the 25 homers came on pitches left over the middle of the plate. No doubt Walker and the Mariners already have figured out whether his high volume of home runs allowed stemmed from a correctable problem or from a simple combination of good hitting and bad luck.
Either way, do not be deceived by Walker's 2015 struggles, and do not fall victim to post-hype apathy. He is a rising star on the cusp of a breakthrough.