Do Prospects Like Aaron Sanchez Improve Their Control? An Investigation

(Photo credit to Keith Allison

Aaron Sanchez is a divisive figure these days. His abilities have long been held in high regard by scouts and prospect evaluators, yet his statistical record hasn’t matched up. Sanchez throws in the mid-90s with a plus curveball, has a starter’s build and a pretty clean injury history. At the same time, his minor league strikeout and walk numbers have rarely been good. He’s walked 4.8 batters per nine over his MiLB career, and last season across New Hampshire and Buffalo, he only managed 7.5 K/9 and carried a 5.1 BB/9.

After a successful 33-inning stint in the bullpen last year, Sanchez has been bad as a starter in 2015, walking more batters than he’s struck out, leading to a 123 xFIP-. His ERA is fine at 3.62, but that’s a product of the defense behind him and good batted ball and sequencing luck. In every start but one (April 27 at Boston), Sanchez has struggled mightily to throw the ball in the strike zone with any consistency. Yet the organization appears committed to him starting for the next little while as they recently chose to keep him up while demoting fellow struggling rookie pitchers Daniel Norris and Miguel Castro.

I don’t expect Sanchez to be an acceptable starter this year and the projections agree: Fangraphs Depth Charts, which aggregate Steamer and ZiPS projections, foresee a 4.74 ERA and 4.79 FIP. Baseball Prospectus’ PECOTA system project a 5.47 ERA and -1.0 WARP over the remainder of the season (19 starts). That puts him on track for a replacement level or worse campaign.

It’s possible that an adjustment Sanchez makes could improve his control at some point and lead to an encouraging season, but he could make that adjustment in Buffalo too. The Blue Jays don’t have great other internal options, but they could consider replacing Sanchez soon with Daniel Norris, should Norris get back on track  with Buffalo and Sanchez continue to struggle. Liam Hendriks has settled in as a useful reliever for the team, but he went three innings in his last appearance and could be stretched out.

At any rate, Aaron Sanchez turns 23 in July and has his whole career ahead of him. Many good pitchers struggled with control in their youth. That he isn’t a quality major league starter right now doesn’t preclude him from being one in the future. He has been ranked among the best prospects in the game for years and we know that there is promise within any highly-rated prospect.

I wanted to investigate what the careers of prospects like Aaron Sanchez tend to look like; pitching prospects who had poor minor league control.

To do so, I produced the list of prospects from 1990-2014 who in the two seasons prior to being named a Baseball America top 50 prospect, walked over 4.4 batters per 9, threw at least 100 total innings and did so in full-season ball (A to AAA). Aaron Sanchez prior to 2015 was named Baseball America’s #27 prospect and tossed 186.2 innings in 2013-2014 between AA and AAA with 4.7 BB/9 and 7.7 K/9.

The 4.4 threshold was chosen because I felt it made Sanchez a good representation of the sample. Then, I connected these prospects to their major league careers by compiling their peripherals through and following their age-26 season (in which the player turned 27 at any point during the year), as well as their total career production. If a prospect made multiple appearances, his latest ranking (and accompanying previous two seasons) was considered.

Here are the 43 comparables, with their Baseball America Top 100 rank, two-season platform minor league walk rate and major league walk rates. Blanks represent a lack of accumulated stats.

IP thru 26
BB/9 thru 26
IP from 27
BB/9 from 27
Archie Bradley920144.8
Henry Owens4020144.427.04.7
Kyle Crick3320145.3
Tyler Glasnow4620144.9
Chris Archer3620134.9352.73.1
Danny Hultzen2920135.4
Manny Banuelos2920124.4
Zack Wheeler3520124.7285.33.9
Chris Withrow4820104.856.05.0
Matt Moore3520105.1347.04.3
Clayton Kershaw720084.91378.32.8
Franklin Morales820084.9256.04.5167.74.3
Scott Elbert3120074.959.
Adam Loewen4520065.9164.05.8
Homer Bailey3820065.4644.03.1354.72.5
Franklyn German4220034.6137.
Rich Harden2920034.5464.73.9463.74.3
Corwin Malone3220024.7
Juan Cruz620024.8275.04.4380.05.0
Ryan Anderson1420024.8
Tim Redding4920014.9405.73.7416.73.7
Kerry Wood419986.8902.74.6477.33.9
Jaret Wright2219975.2497.34.5475.34.1
Joe Fontenot4519974.642.74.2
Billy Wagner1419964.8118.34.6784.72.8
Chan Ho Park1819965.7723.74.31269.34.0
Julio Santana4419954.7305.04.2174.04.6
Brien Taylor1819944.7
John Burke4919944.715.
Terrell Wade2919944.7126.34.9
Jessie Hollins4119936.14.79.6
Todd Jones4219935.4110.03.4962.03.8
Tyrone Hill1019935.9
Jeff Juden2719924.7349.04.1184.04.3
Pat Mahomes2519925.3379.04.6330.05.4
Darryl Kile3419914.9598.34.51567.03.6
Rafael Valdez3619914.95.73.2
Roger Salkeld519914.9189.34.9
Willie Banks1519914.8488.74.4121.74.5
John Ericks3219905.4162.04.1
Mike Stanton1819904.4224.73.3367.04.0
Narciso Elvira2319904.65.09.0
Willie Smith4819905.453.

Despite being within a pretty tight window of prospects, this is a diverse list. Greatness was expected out of pitchers like Kerry Wood and Clayton Kershaw, while others were always seen as lottery tickets. The point of this analysis was to see if well-regarded but control-challenged pitching prospects are able to improve their control after making the major leagues. What matters is that these pitchers all had a level of minor league control similar to that of Sanchez. There was no essentially correlation between rank and MiLB BB/9 in this sample.

For the most part, these prospects improved their walk rates as they transitioned to the Major Leagues. They rarely improved it to the point of it not being detrimental to their career. Here is what happened to the 43 pitchers through their age-26 season:

  • 4 improved their walk rate by a rate of at least 2 BB/9: Homer Bailey, Kerry Wood, Clayton Kershaw and Todd Jones. Control issues did not prevent the first three from becoming front-line pitchers. Jones had a respectable relief career.
  • 5 improved their walk rate by a rate of 1-2 BB/9: Chris Archer, Willie Smith, Chan Ho Park, Tim Redding and Mike Stanton.
  • 7 improved their walk rate by a rate of 0.5-1 BB/9.
  • 9 improved their walk rate by a rate of 0-0.5 BB/9.
  • 3 worsened their walk rate. Franklyn German fell apart completely, increasing his walk rate by 2.36 BB/9.
  • 15 did not record 30 IP in the Major Leagues. This includes six current prospects who likely will reach the threshold. 8 others washed out, likely a result of their control not improving. John Burke pitched 59 innings at age 27, washing out afterwards.

The average improvement of the pitchers who did record 30 innings was 0.74 BB/9. However, that is likely inflated by survival bias since it does not include the pitchers who did not justify major league time. If we include the nine prospects who are not current prospects and did not record 30 innings and assign them zero improvement, our new average is 0.56.

Here’s a graphic showing the transitions.

Prospects were ranked in Baseball America's top 50 for 1990-2014. Platform MiLB seasons were previous two years of full-season ball a prospect recorded prior to beiong ranked. If a prospect made multiple lists, their most recent year was considered. 30 MLB innings required for charting.

Prospects were ranked in Baseball America’s top 50 for 1990-2014. Platform MiLB seasons were previous two years of full-season ball a prospect recorded prior to beiong ranked. If a prospect made multiple lists, their most recent year was considered. 30 MLB innings required for charting.

What happens after the age of 26, when pitchers have had even more time to practice repeating their delivery? 25 of our pitchers did not record 30 IP after the age of 26 (11 current pitchers have not had a chance to) while the average improvement of pitchers who did was 1.0 BB/9. These pitchers improved by an average of 0.13 BB/9 compared to their rates through age 26, although most of that improvement is due to reliever Billy Wagner. These pitchers who had control issues as prospects did not really continue to improve as they progressed deeper into their careers. And a further five washed out after having pitched through age 26.

What can we learn about Aaron Sanchez through these pitchers? It’s important to note that he has not shown the strikeout capabilities that his prospect pedigree would suggest. In fact, his platform strikeout rate would rank fourth from the bottom. Another article could be written analyzing prospects with his strikeout history. The prospects in the sample I’m analyzing averaged nearly ten strikeouts per nine in their minor league platform, and linearly fitting Sanchez’s minor league strikeout rate on the line of pitchers who threw 30 innings through age 26 would leave him with 6.7 K/9, which is essentially what he’s averaged so far. Sanchez isn’t that similar to Kerry Wood and Clayton Kershaw, but the control strides those two great pitchers made is encouraging.

While he isn’t a huge strikeout pitcher, 28.8 was the average prospect rank of my sample and Sanchez has been ranked #27 and #32 in the last two years, so his overall talent package is representative. An improvement to ~4.1 BB/9 would probably not turn around his career completely but he has increasingly become an extreme ground ball pitcher and if he can hold that batted ball profile constant and improve his strikeout rate slightly, the control improvement may make him a productive back-end starter for the Blue Jays. These comparable players don’t paint a great picture though and it will be hard for me to buy in without first seeing him make the requisite gains.

Chris Mitchell’s KATOH prospect projection system projects a mediocre 2.5 WAR through his age 28 season. That’s above many  prospects who the industry uniformly believes will exceed 2.5 WAR, so the projection shouldn’t be taken as gospel, but it backs up the fact that peripherals like Sanchez’s have not been conducive to success.

Aaron Sanchez is 22 years old and a long-time top prospect, and the Blue Jays clearly agree that he has a lot of ability. These facts, however enticing, do not excuse his poor control history. It is unreasonable to expect that his control will sort itself out and that he simply has standard developmental gains left to realize. The walks present a roadblock to his long-term outlook.

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Author: Spencer Estey

Spencer has been a baseball fan since a young age and, being from Toronto, he has always been partial to the Blue Jays. He is a statistics major at the University of Waterloo and is intensely interested in the analytic aspect of the game. Spencer follows baseball by watching countless games each season, reading various advanced analysis sites, playing in deep dynasty fantasy leagues and discussing the game with fellow fans.

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