Luis Castillo has the highest walk rate (13.0%) of all qualified starting pitchers.

This isn’t a new problem for the Cincinnati ace. He has repeatedly escaped damage, allowing two runs or fewer in six starts with at least four free passes. Those baserunners finally caught up to him last Saturday. Castillo still sports a 2.56 ERA after surrendering six runs (four earned) against the Brewers, but there are reasons to worry about him remaining a fantasy ace.

Pitcher List’s Alex Fast recently broke down the limitations of first-pitch strike rate, which can oversell a pitcher’s success getting ahead of the count if he’s simply getting hit early in at-bats. Throwing strikes, however, is kind of a vital skill when it comes to not walking batters. Castillo is also last in this category, opening just 50.4% of his showdowns with a strike. His F-Strike rate was a full 11 points higher last year.

Sure, maybe this won’t spell catastrophe if hitters still can’t .. you know … hit him. He has limited contact (66.1%) more than any other starter in the majors, leading to a microscopic .180 opposing batting average and 109 strikeouts in 91.1 innings. A .189 expected average and 277 expected wOBA are in near full support of his early returns. Yet even a hurler with his elite skills will struggle to consistency strand all of those players permitted a leisurely stroll to first base.

As the walks rise, so has his 3.71 FIP and 4.28 SIERA. This is starting to feel reminiscent of Trevor Bauer’s early-season tightrope act. He dominated in April despite a pair of six-walk outings, but his ERA has climbed from 2.45 to 3.55 since expressing some concerns in this column in early May.

It’d be one thing if Castillo was an ace with a proven track record, but volatility has always been a cost of business. Last year, he approached the All-Star break beaten to a 5.49 ERA before amassing a 2.44 ERA in the second half. Yet to excel over a full season, managers who have ridden him to glory for three months must beware the possibility of a 2019 reversal.

Despite these fears, I have yet to significantly move Castillo down by rankings. He’s flawed, but so is just about every other starter. Most other top-20 candidates have either struggled (Bauer, Patrick Corbin, Aaron Nola) or come with enhanced health and/or workload risks (Hyun-Jin Ryu, Charlie Morton, Noah Syndergaard, James Paxton, Chris Paddack). This isn’t a call to sell Castillo for pennies on the dollar, but don’t get too comfortable with him as a top-shelf ace.

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Charlie Morton: -3 wRC+
That’s how opponents have fared against Morton’s curveball prior to Wednesday’s start at Minnesota. The lethal pitch has yielded a .118/.153/.174 slash line and 59.4% opposing contact rate, per FanGraphs. The returns are even more impressive considering he’s deployed it more often than any qualified starter in baseball.

 
Morton had upped the offering’s dosage in each of his two transformational seasons with the Astros, topping out at 29.3% last season. Seeing the success he had with the curveball, the Rays took it one step further. It’s still baffling hitters and generating an 18.6% swinging-strike rate, so why mess with success? A 15.1 pVAL makes it the most effective curveball in baseball.

For the first time in his career, the 35-year-old righty has thrown his four-seam fastball and sinker less than half the time. This adjustment is for the best. According to Baseball Savant, he has lost over one mph on both pitches, each of which has ceded a .343 wOBA. His heater is nothing special, but his curve still twirls at an elite spin rate.

Morton has ridden the magical pitch all the way to a 2.43 ERA and 120 strikeouts in 100 innings. Prior to facing the Twins, he ranked fourth at SP behind Justin Verlander, Ryu, and Max Scherzer on ESPN’s Player Rater. He’s emerged as an ace and top-10 starter on a per-game basis, but there are also some caveats to beware. The 6’5″ hurler sported a 2.54 ERA through last June before posting a 3.91 ERA over the final three months. He ran out of gas and missed some time in September with a shoulder injury, and yet his 167 innings pitched still set a personal high. Don’t bet on him busting that trend 17 years after getting drafted and tossing 200 frames.

Maintaining high-quality production through 175 innings would mark quite the feat. At this point, durability woes are the only reason not to rank Morton above younger, erratic hurlers like Castillo and Bauer.

Rick Porcello: 84.0% Contact Rate
Porcello hates your fantasy teams. Nobody in a mixed league of 12 teams or smaller messed with him against the explosive Twins on June 17, so of course he amassed eight strikeouts over seven scoreless innings. That made consecutive strong starts from the 30-year-old workhorse, alluring some managers to jump back on board heading into an easier home start against the Blue Jays.

He served up five runs, marking the seventh time he allowed four or more scores in a start. Eric Lauer and Marco Gonzales are the only qualified starters to relinquish a higher contact rate than Porcello, who has a 4.48 ERA since winning the AL Cy Young Award in 2016. It’s not soft contact either; nobody besides Mike Leake has abdicated more barrels.

While always a finesse pitcher who relied more on command than stuff, Porcello posted a career-high 23.5% strikeout rate in 2018. This year, it’s down to 18.6%, his lowest clip since 2014’s swan song with the Tigers. Last season’s 8.7% swinging-strike rate was poor, but his current 7.6% is horrendous. It’s the fifth-lowest of qualified starters.

Porcello continues to ride on the coattails of his one stellar season, even if a 3.78 SIERA and 3.89 xFIP justified Kate Upton’s fury. I’ve been guilty of overvaluing his durability as well, but he’s not worth the hassle in a traditional, non-points mixed league. This is especially true if he’s not going to deliver strikeouts at an above-average rate. He’s a bland, replaceable innings-eater who will have too many duds to ever trust.

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