The reasons for the sudden decline and fall of Tim Lincecum are plentiful.
He scrapped his slider during spring training to save some wear and tear on his elbow, only to begin throwing it again shortly after the season started.
However, even though he's been using the slider, it hasn't been as effective this season. Righties are hitting .283/.352/.478 off of Lincecum this year, and the slider is the primary pitch that he attacks them with.
After bulking up last year to maintain velocity on his fastball, he shed a lot of weight swimming in the offseason, which could explain the drop in velocity.
Pitchers that lose fastball velocity can afford to do so as long as they also decrease speed in their changeup to keep the difference between the two pitches close to 10 miles per hour. Alas, Lincecum's changeup hasn't lost velocity, and there is only a seven MPH difference between his average fastball and changeup now.
He also battled some blister and finger nail issues earlier this season, which prevented him from throwing in between starts for a period of time.
Additionally, he's had a hard time out of the stretch this year. Lincecum has a .268/.369/.430 line out of the stretch, and that balloons to .282/.402/.468 with runners in scoring position.
His command has also been an issue as his walk rate has shot up to 10.3 percent this season from a career low of 7.5 percent in 2009, when he won his second Cy Young Award. The command issues have led to a lot of hittable pitches in the middle of the strike zone.
From a scouting standpoint, it appears to me that Lincecum is late in getting his arm out in front when his left leg plants, which is causing him to miss at the belt or above. Lincecum needs to drive the fastball down below the belt to set up his off-speed pitches, but he has not been able to do that consistently this season.
Whatever explanation you want to use for Lincecum having the fifth worst ERA and the second worst quality start percentage in all of baseball this season, he'll be a free agent after next year. The Giants are currently on the hook to pay him $22 million next year to see if he can rediscover his old form.
Here are four possible options that the Giants have with Lincecum as he approaches free agency.