In Hammel's first five starts, he allowed no more than five hits in any game, despite throwing at least 6 2/3 innings in each appearance. The correction is starting to take place already; Hammel benefited from a .138 BABIP in April, but he has seen that mark rise to .341 so far this month. As the hit rate continues to regress, his WHIP and ERA will likely rise. This is a good time sell high.
Dillon Gee (4.28 FIP) -- FIP (Fielding Independent Pitching) is a useful stat to determine a pitcher's effectiveness. For Gee, there is a major difference between his 2.73 ERA and his 4.28 FIP. A closer look at Gee's other numbers reveals some cause for concern. For starters, the 28-year-old's walk rate is his highest since 2011. Meanwhile, his strikeout rate is his lowest since '10, and the aforementioned FIP is at its highest rate since '11.
Smart fantasy owners won't be fooled by Gee's low ERA, and they will expect it to end up closer to his 3.78 career mark. As his ERA starts to rise, the right-hander's low strikeout rate will start to be more of an issue, and he will likely end up back on waivers in shallow leagues.
Nathan Eovaldi (10 walks) -- The Marlins boast a deep group of young talent, and few of their players are more exciting than Eovaldi. The 24-year-old has shown improved control this season, issuing just 10 free passes in 50 1/3 innings. Compare that walk rate to last season -- when Eovaldi walked 40 batters in 106 1/3 innings -- and it is clear that this young pitcher has learned how to pound the strike zone.
Eovaldi's strikeout rate has also risen sharply this season, and his 2.86 ERA is nearly identical to his 2.93 FIP. Smart fantasy owners who need a pitching boost will try to trade for Eovaldi rather than paying a premium for an established veteran.
Garrett Richards (46 strikeouts) -- Richards has always thrown hard, but he struggled to put batters away early in his career. His K/9 rate was just 6.1 over the first three big league seasons, and that ratio was established mostly in a relief role, where he could come in fresh and did not need to pace himself. This season, while working as a starter, Richards has struck out 46 batters in 45 innings, which has given him a surprisingly big bump to a 9.2 K/9 rate. However, with 20 walks, Richards is still showing questionable control, and those free passes could catch up with him if he cannot finish off hitters with the same effectiveness in the coming weeks.
After seven starts this season, the 25-year-old has given fantasy owners every reason to sit squarely on the fence. As long as Richards maintains his improved strikeout rate, he can continue to have success. But like Hammel, his hit rate has dropped significantly this season. Unlike Hammel, Richards has shown a notable skill improvement, which suggests that his hit rate could stay close to its new mark.
Jordan Lyles (Three home runs) -- When he was with the Astros, Lyles did not do a great job keeping the ball in the yard. But this year with the Rockies, the 23-year-old has been taken deep just three times in 50 2/3 innings. Lyles has ridden the lower homer rate to a 5-0 record and a 2.66 ERA, but fantasy owners should continue to stay away. So far this year, Lyles has posted a career-low 5.7 K/9 rate. In fact, he has whiffed at least five batters in just three of his eight starts. In three other starts, Lyles punched out three batters or fewer.
NL-only owners can ride Lyles' hot start for as long as it lasts, but those in mixed leagues should search for a starter with a better chance of racking up K's and keeping his ERA under 4.00 the rest of the way.
Tom Koehler (3.99 FIP) -- Like Gee, Koehler's FIP gives an accurate picture of a pitcher who is about to see his ERA rise. Because of a 1.99 ERA and a 0.99 WHIP in seven starts, the right-hander is beginning to attract attention from mixed-league owners. Those owners, however, would be wise to tread lightly with the 26-year-old. Koehler's walk rate, strikeout rate and home run rate are nearly identical to his marks in 2013, when he posted a 4.41 ERA and a 1.36 WHIP. Pitchers who cannot fan at least twice as many batters as they walk usually struggle to succeed; and as of now, Koehler is on the wrong side of that list for the second consecutive season.