I see where you're coming from, and thus far, what we've seen at the major leagues indicates just that. A borderline pitcher with decent to good stuff who is young and has room to improve into a more or less league average pitcher. The facet of his game most likely to be improved upon with time is his pitch count and WHIP, which will let him get deeper into games, logging more innings collecting more wins. He allows far too many baserunners because of his intense nibbling. From what we've seen with the big club thats more or less his story.
I've been a big Lester fan since 2003 when he was with augusta. I saw him pitch in '05 in portland two times and again at pawtucket multiple times in 06. I've seen video of more than a few starts at portland when he was eastern league pitcher of the year. The quality of his stuff was not vastly different, but his approach has been. He's always had good stuff at the major league level, just bad results because of a tendency to try to pitch way around guys. At this stage in his career it looks to me like he has Billy Beane syndrome. Dominant in the minor leagues, taking a bulldog approach and attacking hitters from 0-0 and on down into every count. Throwing strikes, being aggressive. Since he has been under the lights in the majors, that hasn't been the story. He looks tentative. Trying to aim the ball to the black, or off of it, afraid of getting punished. When you do that, you run yourself into trouble, someone with lesters quality stuff needs to be putting the ball inside the black - toward the plate. He has the stuff to get away with getting a little too much of it.
Location is partly repeating your delivery, and partly mentality and confidence. When you aim, do you aim to your spot and toward the plate, or off of your spot away to not get hit? When you have Jon Lester caliber stuff, you can afford to miss spots here and there, its just where you miss them. Missed spot for an obvious ball and an easy take, or missed spot for strike that makes the batter have to swing?
Its like when a hitter struts out with a great BP swing, but can't take that stroke into the games and changes his approach at the plate. Lester changes his approach on the mound and he pays for it. He loads up the bases once every four innings, and when you put yourself in those situations, you're gonna pay for it no matter how good you are. He's been a wizard in escaping these jams though, because when the pressure is on to put the ball over the plate, he does and his stuff does the rest. When he masters that consistent bulldog approach up in the bigs, he will begin to come into his own. I think this will be the year he settles down long enough to do just that. After a shaky April and maybe may, I think we'll start to get some big performances out of him and people will start to see what he can do when hes attacking hitters. I think it will happen, it might not, time will tell.