On Thursday we all saw Clayton Kershaw throwing gas, hitting 97 MPH multiple times during the game. Its pretty rare for anyone to throw 97, let alone a left handed starting pitcher. Commenter silverwidow pointed out in the gamethread that Kershaw might be the hardest throwing lefty in the major leagues. Thanks to Fangraphs, we can find out.
Here are the top starting pitchers in the MLB in terms of average fastball velocity in 2008. All starters with at least 10 IP are eligible.
| Pitcher | Average Fastball Velocity |
| Ubaldo Jimenez | 94.9 |
| Joba Chamberlain | 94.9 |
| Dustin McGowan | 94.8 |
| Felix Hernandez | 94.6 |
| Ervin Santana | 94.4 |
| Max Scherzer | 94.4 |
| Brandon Morrow | 94.3 |
| Josh Beckett | 94.3 |
| A.J. Burnett | 94.3 |
| Tim Lincecum | 94.1 |
| Clayton Kershaw | 94.0 |
Apparently if you can average at least 94 MPH wth your fastball you are going to be a stud because this is a pretty amazing group of young pitchers. Clayton Kershaw ranks 11th on the list, but he is also the only lefty. This means that Kershaw is in fact the hardest throwing lefty starter in the majors. Here's the next five lefties:
| Pitcher | Average Fastball Velocity |
| CC Sabathia | 93.7 |
| Jorge de la Rosa | 92.8 |
| Wil Ledezma | 92.8 |
| Manny Parra | 92.4 |
| Jon Lester | 92.1 |
This list is a bit more hit-or-miss. Nothing needs to be said about Sabathia, and Lester and Parra both have promising careers, but Ledezma and de la Rosa have yet to have much sustained MLB success. Ledezma seems to have run out of chances, but de la Rosa is the #4 starter for the Rockies.
There is one caveat to these findings. While Kershaw is the hardest throwing lefty starter in the majors, he's not the hardest throwing if you include relievers. Here's the relievers that throw harder than Kershaw does.
| Pitcher | Average Fastball Velocity |
| Matt Thornton | 95.3 |
| Jeremy Affeldt | 94.6 |
| Billy Wagner | 94.5 |
| David Price | 94.2 |
Matt Thornton takes the crown for the hardest fastball by a lefty in the MLB in 2008. He is a reliever with the White Sox who had a great year in '08 but was mediocre before that. Jeremy Affeldt just signed with the Giants this offseason, so we'll get plenty of chances to see him. Billy Wagner is out for the year because of an arm injury so he'll probably never throw this hard again. David Price is the Rays' phenom who got called up last September and pitched well in the playoffs. Keep in mind that relievers usually get an extra 1-2 MPH added to their fastballs because they can throw max effort pitches for one inning whereas starters have to pace themselves. For example, the last time Jeremy Affeldt was used as a part-time starter (9 GS in 2006) his average fastball velocity was 91.9. I think all of these guys with the possible exception of Thornton would throw softer than Kershaw under equal circumstances.
So there you have it. Clayton Kershaw is the hardest throwing left-handed starter, and probably the hardest throwing lefty in the major leagues. Now he just needs some more control.