December 06, 2011
In Sunday's 35-32 comeback win over the Minnesota Vikings, Tebow tossed a season-high 202 yards. For comparison sake, Aaron Rodgers'(notes) season low was 247 yards and Drew Brees(notes) is averaging 188.75 yards in the first half of games this season — so it isn't like Tebow's numbers are suddenly re-writing the record books. But the second-highest passing total of his NFL career could have been a lot more if he adjusted his awkward throwing form.
"A more sidearm delivery certainly puts the ball's release point lower than a typical NFL quarterback. That bothers coaches because of the possibility of getting the ball knocked down," said Dr. John Eric Goff, Professor of Physics at Lynchburg College and author of Gold Medal Physics: The Science of Sports. "It's also interesting that the ball relies a little more on the fingers for launch speed, compared to a more overhand throwing motion that gets more of the palm involved."
Quite simply, a sidearm throw can complicate things in terms of passing efficiency. Tebow has just a 47.5 percent completion percentage in his second year in the league.
"Sidearm deliveries cause a little more precession in the spin axis because that axis is usually a little more away from the launch velocity compared to an overhand throw which leads to a little more air resistance for a sidearm throw compared to an overhand throw. Lower release points also require slightly greater launch angles for long throws," Dr. Goff said. "A greater launch angle means a longer time of flight, which might give corners a little more time to get to the ball."
So the longer Tebow has to wind up, the more time defenders have to get a bead on the ball. It should be noted that the Broncos quarterback has thrown 10 touchdowns to one interception due to the fact that he's willing to throw the ball away rather than force passes that might get picked off.
Tebow was said to have had a mechanical makeover leading up to last year's NFL draft, where the Broncos made him a first-round pick, but his entire throw is still an elongated, looping motion. It is a far cry from the much-ballyhooed quick release of the Tom Bradys of the world or Dan Marino, whom Dr. Goff cited as the fastest release he ever saw.
It's impossible with numbers and science to dispute Tebow and his team's 6-1 record this year when he starts, but the room for improvement in his game means that he can only get better.
"Just as a simple example, say that a quarterback wants to throw a bomb, nearly 60 yards. The quarterback releases the ball at 50 mph with a release angle of 45 degrees, and the ball is caught at the same height at which it was thrown. The ball goes nearly 56 yards down the field in about 3.22 seconds if we ignore air resistance. A well-thrown spiral doesn't have too much air resistance, so those numbers don't change much when including the air," Dr. Goff said.
"If you drop the arm a foot like in a sidearm throw such as Tebow's, the range is just a tad over 49 yards and the time of flight is about 3.3 seconds. The conclusion of something like a 12 percent reduction in bomb distance is the new result, as long as one assumes the release speed has dropped 5 percent and the release angle has increased five degrees."
The result is a reason why players in the secondary are perhaps making plays on Tebow's throws and knocking down passes.
"The time of flight is just under a tenth of a second longer, which might be enough for a corner to close a little gap that he couldn't otherwise close," Dr. Goff said.
Kristian R. Dyer can be followed at twitter.com/KristianRDyer
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