A couple of National League Central starting pitchers have caught my eye. Both are owned in a lower percentage of fantasy leagues than they should be, and both are flame throwers. One of the two has already received not just one endorsement from Paul Sporer earlier this month, but also a second after pitching decent in Colorado and brilliantly in Arizona. The other hurler hasn’t received the same level of praise, but Jeff Zimmerman noted a new breaking ball this righty’s added to his mix, and his results of late are intriguing.

Luis Castillo (CIN): CBS – 64%, ESPN – 20.0%, Yahoo! – 24%

Castillo made his sixth big-league start yesterday and his second against the Diamondbacks. After shutting them out for 6.2 innings at Chase Field the first time they saw him, he yielded four earned runs in six innings the second go-round. Three were coughed up on a first-inning tater off of the bat of Jake Lamb, but he settled in nicely after that and finished with seven strikeouts and only five baserunners allowed overall. It was yet another encouraging start in spite of a non-helpful ERA in this particular outing. Overall, he’s the owner of a 3.86 ERA (4.56 FIP, 3.64 xFIP and 3.69 SIERA), 1.26 WHIP, 10.3% BB% and 29.5% K% in 35 innings pitched.

Since walking eight batters in his first two starts spanning 10.2 innings, he’s demonstrated improved control with just one hiccup in his next four turns — four walks allowed to the Nationals in six innings. He’s allowed just one walk in each of his other three starts. The 24-year-old’s current walk rate is acceptable given his elite bat-missing skills, but couple his improvements since his first two starts with his 4.1% BB% in 80.1 innings spread across 14 starts at the Double-A level this year, and I believe he’ll whittle his BB% under 10%.

Entering play yesterday, Castillo’s 48.0% F-Strike% was well below the league average of 60.4%, but he poured in first-pitch strikes to 14 of 23 (60.9%) Diamondbacks on Thursday, per ESPN. He also entered the game with a 44.0% Zone% that’s much more in line with the league average of 45.1%. Getting back to his bat-missing skills, though, he’s a stud in that department.

The righty’s 13.0% SwStr% before yesterday’s start was tied for the 20th highest among starting pitchers with a minimum of 20 innings pitched this season. That mark went up yesterday with another 16 swinging strikes in 100 pitches thrown, according to ESPN’s box score. Castillo backs his top-shelf cheddar (97.5 mph average velocity) with a slider that has a 17.8% SwStr% and a changeup with a 21.3% SwStr%. The combo of a breaker and changeup that can net empty swings should help him close a platoon split that featured a .298 wOBA allowed to lefties and .355 wOBA ceded to righties before Thursday’s start. In addition to avoiding contact, his slider and change do a great job of coaxing groundballs with a 87.5% GB% and 56.3% GB%, respectively. His fourseamer does a solid job of inducing worm burners, too, with a 48.9% GB%. The rookie hurler’s ability to keep the ball on the ground (55.7% GB%) will serve him well in his homer-friendly home digs.

Castillo’s been challenged out of the gate facing the Nationals twice, Diamondbacks twice and Rockies once at Coors Field. He hasn’t folded under the pressure of challenging matchups, but he’s on track for one more if he gets the ball on regular rest at Yankee Stadium next Tuesday. Looking ahead, he should draw some more favorable matchups down the stretch — I mean, they can’t get much harder than he’ll have already endured. He might take some lumps as a rookie, but everything in his profile screams top-50 SP for the ROS, and he should be universally owned at this point.

Chad Kuhl (PIT): CBS – 13%, ESPN – 4.0%, Yahoo! – 3%

Velo spikes are attention grabbers, and as Jeff’s linked piece above pointed out, Kuhl’s velo has jumped significantly this year. Among starters who’ve pitched a minimum of 60 innings, Kuhl’s average fastball velocity of 95.3 mph is 11th highest and two full ticks faster than last season. The extra ticks have helped nudge his sinker’s SwStr% up from 4.6% last year to 7.2% this year. It’s not a huge swing-and-miss offering, but the gain is notable, and it might also have helped his other pitches play up.

His changeup’s SwStr% has risen from 7.3% in 2016 to 11.2% this year, and his slider has developed into a true put-away pitch with a 22.2% SwStr% after sitting at just 17.9% in 2016. The slider predictably eats right-handed batters up with a 24.24% whiff percentage and a 58.97% GB% this year, according to Brooks Baseball. The 24-year-old righty hasn’t had much trouble in same-handed matchups with a .299 wOBA allowed to righties this year and a .297 wOBA allowed to the 356 he’s faced since reaching The Show last season.

While he’s done quite well against righties, he’s been beaten up badly by lefties. Last year, he allowed a .363 wOBA to them, and this year he’s yielded a .381 wOBA to them. Don’t write him off against left-handed batters, though! Also noted in Jeff’s linked piece above is the addition of a curve to Kuhl’s repertoire. He didn’t throw a single curve last year, but he’s thrown the pitch at a 3.8% clip this season. Kuhl’s slowly increased his usage by month. According to Brooks Baseball, he didn’t throw the curve in April, threw it 3.38% of the time in May, 6.09% of the time in June and has a 6.67% usage rate this month. Most important for his massive platoon split is that it’s a pitch he’s using more against lefties than righties. Brooks credited him with throwing the curve 2.49% of the time to lefties in May, 7.86% in June and 9.43% thus far this month. Lefties are hammering the curve into the ground this month with a 85.71% GB%, and most remarkably, they’ve yet to record a hit off of the pitch. The curve is responsible for a .091/.091/.364 slash line overall.

Since the beginning of June, Kuhl has made eight starts spanning 41.2 innings and spun a 3.46 ERA (4.09 FIP, 4.04 xFIP and 4.51 SIERA) and 1.32 WHIP with a 10.5% BB%, 20.9% K%, and a 50.9% GB%. Also in that time frame, he’s tied up lefties allowing just a .222/.333/.352 slash and .300 wOBA. The sample is admittedly small (84), but the tangible addition of a weapon to combat them with provides ample cause to speculate on Kuhl’s recent run of success being semi-sustainable. The righty’s next start is at Coors Field over the weekend, and I wouldn’t advocate using him there. After that, though, he projects to square off with the Padres at San Diego and the Reds in Pittsburgh. I would suggest rostering Kuhl in leagues as shallow as 12-team mixers.