After going over some bats last week, it’s pitcher week again here at Buy/Sell.

The last time this column covered pitchers, we looked at two Cubs hurlers to try to buy low (Yu Darvish and Jose Quintana). This week, we’ll look at two other members of the Cubs rotation who could make for appealing sell-high candidates (Jon Lester and Tyler Chatwood).

Kyle Hendricks must be feeling left out right now. Perhaps someday he’ll get his moment in the sun — or shade, as the case may be!

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Players to Buy

Luis Castillo (SP – CIN)
Castillo was a popular breakout pick this spring, but his 7.85 ERA and 1.67 WHIP so far have been nothing short of disastrous for fantasy owners. Castillo’s walk rate is up and his strikeout rate is way down, and while he’s still throwing very hard, his velocity is down some as well. This is what rock bottom looks like for Castillo, but if you are able to buy him at a bargain basement price, you could be richly rewarded.

Castillo hasn’t pitched well no matter how you slice it, but some of the underlying numbers suggest he’s also been remarkably unfortunate. Among pitchers who have thrown at least 20 innings, Castillo has yielded baseball’s 19th-highest BABIP (.330), ninth-highest HR/FB ratio (21.4 percent), and 10th-lowest stand rate (58.1 percent). All of those figures should normalize over time, taking several runs off of Castillo’s ERA even if he doesn’t significantly improve his performance. But there’s hopeful news on that front, too. Reds coaches have identified that Castillo’s arm angle has changed and are working with him to regain the sinking motion on his two-seam fastball.

Castillo’s reduced velocity could at least partly be a result of cold April weather, and his swinging strike rate is actually up despite his reduced strikeout rate. Castillo could still become the valuable fantasy pitcher that many expected heading into the season, and now is the time to acquire him at a fraction of his draft-day cost.

Zack Greinke (SP – ARI)
Greinke was the 11th pitcher off the board in fantasy drafts this spring, but his bloated 4.50 ERA could have his owners thinking of him as more of a second or third fantasy starter, rather than an ace. If so, he’s worth buying.

Greinke’s .315 BABIP allowed and 17.6 percent HR/FB ratio allowed are both among the highest in baseball, and his 70.6 percent strand rate is among the lowest. All of those data points should improve over time, particularly the HR/FB ratio, now that the installation of a humidor appears to have made Chase Field into much less of a bandbox.

It is important to note that Greinke’s velocity is down a bit, but that hasn’t affected his ability to miss bats. His 13 percent swinging strike rate is the highest of his career, and currently 17th-best in baseball. And his 10.50 K/9 is currently the second-highest of his career, ever-s0-slightly behind the 10.54 K/9 he put up during the 2011 season.

Add it all up, and Greinke still deserves to be considered among the 12 best starting pitchers in fantasy baseball.

Lance McCullers (SP – HOU)
When I’m investing in pitchers, I love to get guys who have two things going for them 1) a high strikeout rate and 2) a high groundball rate. While grounders do tend to produce more base hits than fly balls, pitchers that induce a lot of grounders generally allow far fewer home runs, and if they miss a lot of bats, base hits usually aren’t too big a problem, either.

McCullers is as good as it gets when it comes to a combination of ground balls and strikeouts. Among pitchers who threw at least 100 innings last year, McCullers was fourth in baseball in groundball rate and 19th in K/9. This year, he’s first in ground ball rate and eighth in K/9.

Other than McCullers, the only pitchers with a K/9 over 9.00 and GB rate at or above 50 percent are Carlos Martinez (1.43 ERA), Charlie Morton (1.72 ERA), Hyun-Jin Ryu (2.22 ERA), Patrick Corbin (2.25 ERA), and Luis Severino (2.61 ERA). But McCullers’ ERA currently sits at 3.71 because his .330 BABIP allowed, 15.8 percent HR/FB rate allowed, and 72.2 percent strand rate are all a bit worse than they should be. Expect his ERA to eventually settle much closer to the 3.22 ERA he put up in 2016 than to the 4.25 ERA he had last year.

Of course, McCullers has been great in his last three starts, so you may find that the buy-low window has already closed. If so, try for another pitcher who gets plenty of ground balls and strikeouts, Zack Godley.

Players to Sell

Jon Lester (SP – CHC)
Lester has been a top-tier fantasy starter for the last decade, so many people might look at his strong start to the 2018 campaign and conclude that his 4.33 ERA last year was a fluke. But Lester showed some troubling cracks in the armor in 2017 that have only worsened this season, despite his shiny 2.73 ERA.

Lester’s velocity dropped 1-2 ticks last season, and it hasn’t recovered this year. But unlike Greinke, who’s also lost some mph in his age-34 season, Lester’s reduced velocity seems to be impacting his strikeout rate. It’s also corresponded with an increased walk rate, perhaps a sign that Lester has had to sacrifice some command to even throw as hard as he currently is.

Lester’s ERA is largely a function of his .253 BABIP allowed, which is 44 points lower than he typically yields, even though hitters have been having much more hard contact against him than usual. He should still be an above-average pitcher, but look for his ERA to again hover around 4.00 for the rest of the season.

Aaron Nola (SP – PHI)
Maybe someday Nola will be a number one fantasy starter, but if someone in your league believes this is the year, I’d sell.

Nola’s 2.58 ERA and 0.97 WHIP look fantastic, but he’s simply not missing enough bats to expect those kinds of results to continue. Nola is striking out just 6.57 batters per nine innings, and his pedestrian 9.1 percent swinging strike rate indicates that is no fluke. He’s getting by on a .236 BABIP allowed — almost 70 points lower than his career mark — and a 5.9 percent HR/FB ratio that is less than half the number of home runs he typically surrenders. Regression beckons.

Don’t get me wrong, Nola is a talented young pitcher, and I still expect him to post an ERA in the 3.50-3.75 range with a more serviceable K/9 rate going forward. But based on his pedigree and surface stats, someone in your league might be expecting a lot more from him than that.

Tyler Chatwood (SP – CHC)
If you’re looking to deal Chatwood — and you should be — try playing the Coors Field card. It goes something like this: Chatwood has spent most of his career up to this point pitching for the Rockies, and he was constantly victimized by Coors to the tune of a 5.17 ERA and 1.57 WHIP. He was light years better on the road, where he posted a 3.49 ERA and 1.23 WHIP in 2017 and a 1.69 ERA and 1.11 WHIP in 2016. Now pitching his home games on the North Side of Chicago, Chatwood will rarely have to set foot in Colorado, and he’s got a 2.83 ERA to show for it this year.

Do I have you convinced? It’s a pretty solid argument in some respects, and I wouldn’t be surprised if getting out of Colorado shaves a half run off of Chatwood’s ERA. But right now Chatwood’s ERA is almost two runs lower than it was last year, and he’s not pitching anywhere near well enough to warrant a sub-3.00 ERA.

Chatwood has boosted his strikeout rate in the early going, but he’s still not striking out a batter per inning, and his already poor walk rate from 2017 has gotten completely out of hand this year. Chatwood has walked 22 batters in his first 28 2/3 innings, and the only reason that hasn’t blown up in his face is quite a bit of good fortune. His .264 BABIP allowed, 4.5 percent HR/FB ratio allowed, and 81.3 percent strand rate are all almost certain to regress over time.

Bottom line, Chatwood will never be a major asset in the strikeout department, and he walks too many batters to be a sub-4.00 ERA pitcher, let alone sub-3.00.

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Andrew Seifter is a featured writer at FantasyPros. For more from Andrew, check out his archive and follow him @andrew_seifter.