One of the most common questions people ask me is to name good pitchers who have bad mechanics. Of course, mechanics are too nuanced to draw lines in the sand of “good” and “bad,” but the question is fascinating nonetheless. The general rule is that the best pitchers have excellent mechanics, but it’s true that some of the top players in the game have flaws in their deliveries.

Some of these pitchers have learned to overcome their physical obstacles, while others cover for their deficiencies with filthy stuff. A handful of the game's best pitchers theoretically have room for further improvement; mechanical adjustments could potentially lift their performance to stratospheric status or extend the duration of excellence as they drift further from their physical peak, at which point velocity declines and pitch command becomes a more critical aspect of success.

The ability to make mechanical adjustments has been a hallmark of some of the best pitchers of our generation. Roger Clemens relied on an over-the-top curveball in his early twenties, replacing it with excellent posture and a mean splitter later in his career. Randy Johnson always had the height and the heat, but he completely revamped his delivery to take advantage of his natural gifts and evolved into one of the greatest pitchers of all time. Fast-forward to today and Felix Hernandez has quietly honed his mechanics over the last several years to address the foundational weaknesses in his delivery, allowing him to maintain elite status despite the dissipation of his fastball.

The following pitchers are among the best in the game, but each would receive a below-average grade in one or more subjects on the mechanics report card. They’re the exceptions to the rule, with each player representing a lesson in how such inefficiencies can be overcome at the highest level—and in some cases, how an oddball delivery has led to an elevated tier of success.

Pitcher: Cliff Lee
Deficiency: Balance
Implication: Repetition

Lee lacks balance during crucial moments of the delivery, and his overall tendency is to lean back toward third base en route to the plate. The issue begins during the lift phase; while a well-balanced pitcher will keep his head positioned above his center of mass, Lee's dome is already shading behind his back-side as he reaches maximum leg lift. He also uses a minor twist of the torso at max lift with a reverse-rotation of the hips, a style that King Felix has popularized in recent years.

The imbalance worsens as Lee approaches foot strike, with his entire upper body leaning backward as he prepares to fire the rotational elements of his delivery. Someone could PhotoShop a limbo pole into the following freeze frame, and it would appear that Lee was playing an entirely different game.

Lee also has a blatant drop-and-drive in his delivery, which involves a drastic lowering of his center of gravity. This can be seen in the GIF as well as the photos, particularly by noting the position of Lee's hat compared to the uniform of Jason Heyward—from this camera angle, Lee's head has gone from just below Heyward's letters at max leg lift to just below the belt near foot strike.

The imbalance has a ripple effect on Lee's posture, which is worse than one would expect from such an elite pitcher, though it exceeds his grade for balance. Pitchers with poor balance often battle to repeat their delivery and find a consistent arm slot, and though Lee used to fall in this category (he was tough to watch in his Cleveland days), he is now the poster boy for pitch command and repetition. He hasn't posted a walk rate above five percent since he left the Tribe, and he might have the best fastball command in the game today. It is exceedingly rare for a pitcher to improve his performance in light of such weak balance without a concurrent mechanical adjustment. Lee is the perfect example of a pitcher whom coaches just have to accept, since he’s mastered his flawed delivery.

Pitcher: Chris Sale
Deficiency: Balance
Implication: Repetition

Sale has the same diagnosis as Lee, but the manifestation of his imbalance is much different. For starters, Sale's balance is quite strong into maximum leg lift, as he basically keeps his head above the body with stability above his lanky frame.

His balance flies off the handle once the leg starts to come down and he initiates the momentum phase of his delivery, though the Sale lean heads in the exact opposite direction of fellow lefty Lee’s. Sale hunches over during the stride phase, with the head drifting far out in front of his body between max lift and foot strike. There is a ton of head movement during this portion of his motion, particularly just before he spreads his wings into the inverted-W pattern that is so visually disturbing to coaches, women, and children.

Somewhat miraculously, Sale rights the ship after foot strike, as the head pops up and he straightens his spine angle to finish with near-perfect posture into release point. There is still a semblance of imbalance, as the back foot comes off the ground prematurely (prior to release), though his release-point mechanics are essentially spot-on. Even his glove position is solid despite some serious flail after the baseball leaves his hand.

Once again, it is extremely rare to find a pitcher with such a high degree of mechanical repetition when he suffers from so many faults in his balance. Sale's frame adds further awe to his performance, but it speaks volumes about his functional strength that the southpaw can maintain consistency while having to hurdle such obstacles.

Pitcher: Jered Weaver
Deficiency: Posture, Stride
Implication: Release Distance, Repetition

Weaver has an extremely closed stride, directing his momentum far to the right of the plate in an attempt to create a difficult angle on hitters. Some pitchers require a closed stride in order to line up the gears and reach ideal extension at release point, but Weaver over-exaggerates his direction beyond anyone's natural signature. When the above GIF is captured at foot strike, it appears that Weaver is about to unleash a projectile aimed directly into the opposing Twins' dugout at Target Field.

Weaver received a lot of attention in the spring for his arm slot, as his over-the-top motion had become increasingly exaggerated over the years and he was attempting to bring things down a notch. Sam Miller detailed the situation in an article in late March, using photographic evidence from spring training to look for any adjustments. In the comments section of that piece, I noted that there are two aspects to an arm slot—one is the degree of spine tilt, and the other is the amount of shoulder abduction (elevation) that the pitcher employs. In Weaver's case, it appeared that while his angle of abduction had lowered, his poor posture was still a culprit that was artificially raising his arm slot, and the in-game evidence from late in the season corroborated this claim.

Weaver is an exaggerated case of extreme angles, from the ultra-closed stride to the excessive spine-tilt, and the resulting funk has helped to cover for his declining velocity and limited distance at release point. Those elements alone are obviously not enough to explain his level of success in the majors; Weaver follows the examples of Lee and Sale in that he has learned to coordinate his unique delivery in spite of the self-inflicted challenges in his mechanics. Weaver repeats his delivery very well for a pitcher who fights his natural signature every step of the way, and though his template is not one to be copied, each passing year makes it tougher to argue that he should revamp his motion.

Pitcher: Kenley Jansen
Deficiency: Momentum, Posture
Implication: Release Distance

Jansen has been one of the best relievers in baseball over the past two seasons, following the Mariano Rivera blueprint with a cutter-heavy approach that has been extremely effective despite the fact that opposing batters know what's coming. That he does so with such mechanical barriers to success further deepens the mystery. The right-hander has very tepid momentum that borders on slow, which is especially intriguing when it’s coming from a power reliever who is used for such short bursts. Further confusing the issue is that Jansen uses a very low leg lift in his delivery, stopping his knee below the waist line at max lift.

One might expect such a muted lift sequence with a runner on first base, but this clip was taken with the bases empty. Typically, a pitcher with slow momentum and a short lift will have an extremely shallow stride, but in this respect Jansen defies convention once again—he actually delays foot strike as he glides down the mound, finding an above-average stride length despite all of the barriers. It's the calm before the storm, because Jansen bursts with exceptional torque once his front foot finally plants into the ground.

Jansen further compromises his delivery with excessive spine-tilt from foot strike into release point, which acts to steepen his downhill plane yet shortens his release distance. The trade-off has been working well for him, and the lessened workload of a closer might relieve some of the injury concerns associated with such a delivery, but a pitcher who relies on so much upper body to transfer energy to the baseball is working under conditions of elevated risk.

Pitcher: Clayton Kershaw
Deficiency: Momentum / Gear-Shift
Implication: Repetition, Timing

We saved the best for last. Kershaw is not a cautionary tale so much as he is a modern marvel of mechanics. His delivery gets better every season in terms of efficiency and repetition, and his four-pitch mix might be the nastiest arsenal in the majors. These elements, in conjunction with his left-handedness, represent the best that pitching has to offer in 2013. With this in mind, Kershaw's ridiculous pattern of momentum is merely a sideshow act, and though his multiple-gear shift can be confusing when broken down into stills, a Kershaw GIF is easily worth a thousand words.

Kersh has three speeds on his way to the plate. He leads with the front hip for a strong move into maximum lift, but then his forward momentum comes to a halt as the leg comes down near the ground. When the clip is halted at these two points in the delivery, it almost looks as if he has gone back into the set-up position, with the lift leg in contact with the ground.

Just when it looks like Kershaw is going to balk, he explodes toward the plate with a charge of momentum. Left-handers are known to have extra funk in their mechanics, but there is no delivery in baseball that invokes such a peculiar three-speed pattern from first movement into foot strike.

Such an abrupt strategy should be nearly impossible to repeat, which in turn should throw release points out of whack and wreck pitch command. Sure enough, Kershaw struggled with command and repetition early in his career, but like Lee before him, the Dodgers ace has since mastered his eccentric delivery at an expert level. There is no ceiling that can contain a pitcher with Kershaw's combination of raw talent and accelerated learning curve.