I wanted to get this out last weekend, but here you go. Here is a list of pitchers who should show improvement in their ERA/WHIP going forward based on their xFIP. If you need a refresher, I wrote about xFIP here.
These stats are through April 30th courtesy of Fangraphs:
| Name | K/9 | BB/9 | K/BB | HR/9 | WHIP | BABIP | LOB% | ERA | xFIP | ERA - xFIP |
| Edwin Jackson | 4.73 | 2.78 | 1.70 | 1.39 | 1.76 | 0.362 | 57.70% | 8.07 | 4.59 | 3.48 |
| Aaron Harang | 7.22 | 1.87 | 3.86 | 1.87 | 1.51 | 0.353 | 61.10% | 6.68 | 3.84 | 2.84 |
| Gavin Floyd | 6.89 | 3.86 | 1.79 | 0.83 | 1.81 | 0.385 | 58.40% | 6.89 | 4.31 | 2.58 |
| Justin Masterson | 10.46 | 4.05 | 2.58 | 1.35 | 1.80 | 0.42 | 65.30% | 5.40 | 3.11 | 2.29 |
| Joel Pineiro | 4.85 | 1.52 | 3.20 | 1.21 | 1.52 | 0.347 | 64.40% | 5.76 | 3.91 | 1.85 |
| Josh Beckett | 6.56 | 3.28 | 2.00 | 1.01 | 1.57 | 0.343 | 61.10% | 6.31 | 4.46 | 1.85 |
| Max Scherzer | 5.91 | 3.09 | 1.91 | 1.69 | 1.56 | 0.323 | 58.30% | 6.47 | 4.80 | 1.67 |
| Joe Saunders | 3.82 | 4.11 | 0.93 | 2.05 | 1.79 | 0.316 | 64.90% | 7.04 | 5.40 | 1.64 |
| Brandon Morrow | 10.61 | 5.14 | 2.06 | 0.96 | 1.46 | 0.324 | 67.00% | 5.46 | 3.83 | 1.63 |
| Ben Sheets | 4.75 | 4.75 | 1.00 | 1.78 | 1.91 | 0.341 | 66.50% | 7.12 | 5.64 | 1.48 |
| Homer Bailey | 8.58 | 4.13 | 2.08 | 1.27 | 1.76 | 0.384 | 69.00% | 6.04 | 4.60 | 1.44 |
| Bronson Arroyo | 6.38 | 3.44 | 1.86 | 0.98 | 1.36 | 0.293 | 58.20% | 6.14 | 4.73 | 1.41 |
| Tim Wakefield | 5.60 | 2.63 | 2.13 | 1.65 | 1.57 | 0.333 | 62.20% | 6.59 | 5.23 | 1.36 |
| Jake Peavy | 7.82 | 5.30 | 1.48 | 1.01 | 1.60 | 0.315 | 64.30% | 6.31 | 5.02 | 1.29 |
| Jamie Moyer | 4.50 | 1.50 | 3.00 | 2.10 | 1.33 | 0.287 | 66.30% | 5.70 | 4.44 | 1.26 |
| Dan Haren | 9.23 | 2.25 | 4.10 | 1.35 | 1.30 | 0.334 | 71.10% | 4.50 | 3.33 | 1.17 |
| Scott Baker | 6.62 | 2.55 | 2.60 | 1.02 | 1.50 | 0.346 | 67.50% | 5.35 | 4.21 | 1.14 |
| Cole Hamels | 10.24 | 2.79 | 3.67 | 1.63 | 1.42 | 0.356 | 77.90% | 4.42 | 3.31 | 1.11 |
| Zach Duke | 4.50 | 4.24 | 1.06 | 1.32 | 1.71 | 0.319 | 67.90% | 6.09 | 5.00 | 1.09 |
| Jake Westbrook | 6.03 | 4.88 | 1.24 | 1.15 | 1.69 | 0.322 | 70.00% | 5.74 | 4.72 | 1.02 |
As you can see, most of these pitchers have experienced abnormally high BABIP and extremely low LOB% for the first month of the season, and could provide value going forward should you get them on the cheap.
Since the beginning of May, Edwin Jackson, Ben Sheets and Max Scherzer have not fared too well, but may be available on the waiver wire in mixed leagues. Cole Hamels and Jake Peavy both pitched very well in their first May starts.