I have a friend, who for the life of him couldn't understand they the Minnesota Twins would be interested in a deal centered around Jon Lester. I tried to explain to him the potential of Jon Lester. There's no arguing about Lester's stuff - it's great. When Lester first came up to the Double-A level in 2005, he posted an ERA of 2.61 while striking out 163 batters over 148.1 innings of work.
Going into that season of 2005, Baseball America ranked Lester as the Red Sox fourth best prospect, one spot behind Jonathan Papelbon. After the 2005 season, Baseball America ranked Lester as the Red Sox second best prospect, behind only Andy Marte. Marte was only a member of the Red Sox for a small period of time, and was later dealt to the Indians for Coco Crisp. So for all intensive purposes, Lester was ranked as the organization's best prospect, at any position.
In 2006, Lester was promoted to Triple-A where he again was very successful. In just over 46 innings, Lester had an ERA of 2.70, while striking out 43 hitters. On the surface, Lester looked poised to make the leap to the majors. And Lester did on June 10th. Lester even went on to win his first five decisions, and five of his first seven starts. Over those starts, his ERA as low as 2.38. ESPN compared the young lefty to other young pitchers Jered Weaver and Francisco Liriano. Lester's success, however, masked a major issue in his development.
Starting with Lester's promotion to Triple-A in 2006, his control began to suffer greatly. His walk rate jumped to 4.82 walks every nine innings of work. When he stopped hitting his spots, the typically precise pitcher saw his hit rate, home run rate and WHIP rise as his strikeout rate took a slight dip.
Lester's poor control is what now sets him apart from Type A pitching prospects such as Clay Buchholz and Phil Hughes. This can be demonstrated by a quick comparison of their walk rates at the Double-A level. I chose the Double-A level because it's the only level at which any of these pitchers have thrown at least 85 innings.
In 2005, Lester walked a batter every 2.6 innings of work at the Double-A level. At the same level, in 2006, Hughes walked a batter every 3.63 innings of work. This year at the Double-A level, Clay Buchholz walked a batter every 3.95 innings of work. Over just 100 innings of work, that's a difference of 13 free passes between Lester and Buchholz, or difference in .13 in WHIP.
Exactly what caused Lester's loss of control is debatable. And it's not a matter to be taken lightly. The cause of his control issues could have a lot to do with his future level of success or failure. Some have argued that Lester's cancer may have played a role. Lester himself admits that his 2006 performance was affected by his cancer at some point in the season, although he doesn't say when. It was clear that by the time he came to the Red Sox in June of 2006, his velocity was down three or four miles per hour from where it typically was.
No one but Lester can know how much his illness affected his performance. Even if he was in perfect health, jumps in his walk rates aren't surprising for someone who had less than 50 innings of experience above the Double-A level, before going to the majors. In fact, a rise in walk rates is typical of most pitchers when they are promoted a level. These spikes in walk rates, however, are usually temporary. Some pitchers take longer than others to then get their walk rates down to normal levels. Some pitchers never reduced their elevated walk rates.
Whether Lester will be able to get his walk rate down in 2008 has yet to be seen. Lester now has a total of 118.1 innings of experience at the Triple-A level and 144.1 innings of experience at the major league level. Compared to his first major league stint, Lester now has over 200 more innings of experience above the Double-A level. Still, he wasn't completely healthy for much of that time.
One person who thinks Lester still has the potential to be a great starter is pitching coach John Farrell. Farrell has told the Red Sox management that he thinks Lester could win anywhere from 15-18 games once he's fully developed. In my opinion, Lester has the raw ability to do so. Last year, Lester kept his major league ERA down to 4.57, even while he walked nearly a better every other inning.
Without a significant improvement in control, however, Lester will never win 18 games. Throughout his minor league career, Lester averaged 3.78 walked per nine innings of work. When he keeps his walk rate below four walks every nine innings, he's been successful. His walk rate was below 4 BB/9 IP when he posted a 2.61 ERA at Double-A in 2005 and when he posted a 3.89 ERA at Triple-A last year. So a walk rate below 4 BB/ 9 IP is what I'm going to look for next year.
Who knows, perhaps he could live up to his potential next year. I think it will probably take him another half a year at least before he begins to realize his ability at the major league level. It could take him as long as two more years. Lester is only 23 years of age, and was hurt by being rushed to the majors, and enduring a year of poor health.
He's already shown he has heart, coming back from cancer to win the deciding game of the World Series. Now it's just a matter of putting the ball where he wants it to be. Not that that's an easy task. Major leaguers have long lived or died by their ability to do it. As they say, it's a game of inches.