Dan Haren has always been hard to figure out. How can a pitcher be so good for long stretches, then sour for the second half of seasons?

This is his strangest season yet. Sure, there are some numbers suggesting his 4.65 earned run average (ERA) is largely the product of crummy luck, like his .342 batting average on balls in play (BABIP). However, by far the biggest problem is his 1.48 home runs per nine innings rate (HR/9).

That figure is 0.52 higher than last season and 0.51 higher than his career rate. His home runs per fly ball (HR/FB) is also at a career-high, 14.1 percent.

The good news is Haren's poor performance seems isolated to homers. His K/BB is a magnificent 5.19 (third year in a row with a rate above 5.00). His 4.10 Fielding Independent Pitching rate (FIP) is also well higher than his 3.46 xFIP (expected FIP, which normalizes home run rates), meaning, with an average HR/FB, his ERA would be much prettier.

The bad news is Haren usually makes his fantasy owners a profit with his outstanding first halves, so it's hard to have faith that he can turn things around when he traditionally struggles more and more as the season progresses.

As in Haren's case, home runs are notoriously hard to predict or figure out. Where is the line between luck and skill?

Here are some pitchers who have been at the opposite end of the spectrum from Haren -- their HR/FB rates are among the lowest in baseball. Which ones can keep it up, and which ones do fantasy owners need to worry about?

Felipe Paulino, Astros

Tipping Pitches has doled out plenty of love for Paulino in recent weeks because of his solid 3.27 FIP and 7.95 strikeouts per nine innings (K/9), but the dude is bound to serve up many more gopher balls heading forward.

Paulino's HR/FB is 1.9 percent. He's allowed two home runs in 86 innings this season. For comparison's sake, he allowed 20 in 97.2 innings last season (16.9 percent HR/FB). Toss in the fact that Paulino plays in a homer-friendly park -- Minute Maid is 11th in home runs -- and he looks like a solid bet for a big HR/FB increase moving forward.

Clay Buchholz, Red Sox

As solid as Buchholz has looked, he has an unsustainable 3.7 percent HR/FB rate so far this season. Since his K/9 is rapidly evaporating (it's down to a career-low 6.13), he will be even more dependent on the whims of batted balls. Buchholz could be due for a harsh correction in HR/FB simply because his low K/9 keeps a lot of balls in play.

Buchholz produced 14.7 and 15.7 HR/FB rates his first two seasons. It looks like this year is the aberration.

Other worry guys: Ubaldo Jimenez plays in a homer-friendly park (Coors Field is ninth in home runs) and has a HR/FB below his career rate, so it could be in for a slight rise. This is a way of saying that in addition to being insanely good, Jimenez has been insanely lucky so far and things are bound to change. He will still be good, just not this good ... U.S. Cellular Field is the third best park for homers, which means John Danks could see his 5.3 percent HR/FB rise as the season goes on.

Cliff Lee, Mariners

Lee has the league's second lowest ratio at 2.3 percent. So why shouldn't you worry about him? Because he's produced rates of 5.1 and 6.5 percent the past two seasons. That means a small correction is possible, but he's proven the ability to maintain a very low HR/FB through an entire season.

Francisco Liriano, Twins

Liriano is another low-rate, low-worry guy, and if for no other reason than his best pitch (slider) is nearly impossible for batters to drive far. Now distanced from Tommy John surgery, it appears he has the slider back and working well. It's rated at 13.1 runs above average so far in 2010.

Liriano's home field (Target Field) is 28th in home runs this season, so for now, there's little reason to think a big HR/FB correction is looming.

Other low-worry guys: Anibal Sanchez has a friendly home park (22nd in home runs) and a 7.6 percent career rate ... Matt Cain also has a pitcher-friendly park (24th in home runs) and a nice 6.5 percent career rate ... Clayton Kershaw's home park is mid-pack (16th), but his 4.8 percent this season is actually up slightly from last year ... Jaime Garcia plays in a good place for keeping flies in the park (25th) and his 57.7 GB% suggests he can keep a low HR/FB ... Josh Johnson's 4.7 percent rate is close enough to his career 7.6 total, owners don't need to worry.

Carl Pavano -- Pavano has walked just one batter in his past 16 innings, pushing his season BB/9 to 1.31. He must limit walks to be effective and that's exactly what he's doing this season. His .267 BABIP is slightly lucky.

Hiroki Kuroda -- Kuroda has been ridiculous over his past three starts, allowing two earned runs in 19 innings. He's struck out 23 and walked four in the same span. Kuroda is the typical no-flash, underrated Fantasy pitcher.

8: Consecutive starts for Josh Johnson allowing one run or fewer. Johnson has truly arrived this season. Johnson's K/9 and BB/9 figures are both slightly improved from his already solid rates last season.

Up: Max Scherzer -- Scherzer's season K/9 is up to 8.26, making him worth starting even with the WHIP risk he presents. His ERA is 3.10 over his past three starts. Scherzer's HR/FB is 14.0 percent, up slightly from his career 11.6 percent career rate. He could see a dip in that area as the season goes on, which will provide some ERA relief.

Up: CC Sabathia -- Sabathia seems to be over his annual slow start. He's allowed three earned runs or fewer in four straight starts and his K/BB is 3.11 in that same span. Sabathia currently has a career-high 50.5 GB%.

Down: Matt Garza -- Garza's strong start is a distant memory by now. He's produced an ERA of 9.00 in his past five starts. Things were especially ugly June 18 when he gave up seven earned runs in 1.1 innings.

Down: A.J. Burnett -- Burnett is notoriously inconsistent with his ERA, but the one thing he always brings to the table is strikeouts. Except this season, that is. His K/9 is 6.60, the lowest since 2000. Burnett's .308 BABIP and 70.3 percent strand rate don't point towards bad luck.

Statistics are current through June 22.

Need more pitches tipped? Send questions and comments to amcfadden@rotoexperts.com. Don't forget to check out our Xclusive Edge Rankings to help with tough lineup decisions.

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