I think it really does boil down to track conditions and rain. These are just off the top of my head recently, perhaps others may remember more incidents. I really can't think of anything from 2011, but these seem like a lot of incidents over the past 3 years. Most appear to be cars going down a wet racetrack. Some are just a matter of track prep.
2009 - Pomona - Constant rain delays and when they finally get to Pro Stock David Beckly spins the tires hard off the line in the left lane and V. Gaines slips down the right lane shutting off early to the win, the very next pair KJ duplicates the left lane troubles and Johnny Gray takes a wild slide in the right lane, rain resumes and the race is called for the day.
POMONA 1 - Pro Stock Round 1 Eliminations
2009 - Atlanta - WJ vs Johnny Gray round 1 after a rain delay. Johnny Gray goes for another wild slide and WJ is loose in the other lane to a much lesser degree. Johnny is visibly angry getting out of the car and tells Gary Gerould "You don't want to interview me right now." Rain then resumes and the rest of round 1 is held off until later.
ATLANTA - Rain Delays Eliminations
ATLANTA - Pro Stock Round 1 Eliminations (Corrected)
2009 - Reading - The sun comes out and after a rainy week leading up to the race they make thru 5 pairs of cars in round 1 of Pro Stock. WJ blasts terrible track conditions after skating to the finish line against Larry Morgan. Makes comments that NHRA only cares about the .01% of the cars that make up the sport so the tracks spend money on sand traps instead of track surfaces.
Warren Johnson Gets angry Track Safety Reading PA. 2009 - YouTube
READING - Pro Stock Round 1 Eliminations
READING - Jeepers, Creepers...No Racing 'Cause of Weepers
2010 - Phoenix - Gordie Rivera and Vinny Deceglie both have nearly identical flips in the left lane. The rain comes in and delays sundays eliminations and after round 1 the Pro Stock class move the balance of their eliminations to Gainesville.
PHOENIX - Pro Stock Qualifying Notes, Session #2
PHOENIX - Pro Stock Qualifying Notes, Final Session
PHOENIX - Pro Stock to Finish in Gainesville
2010 - Seattle - Shane Gray defeats V. Gaines while both shut off after skating down an iffy track. WJ vs Ron Krisher are in the next pair and WJ gets loose then AGAIN blasts NHRA track prep and comments "Hell Ray Charles can drive one of those damn things" The rest of round 1 heads back to the pits.
Ron Kirsher Warren Johnsons Temper Flares Up Safety Pro Stock Round 1 Eliminations Northwest Nationals Seattle 2010 - YouTube
SEATTLE - Pro Stock Round 1 Eliminations
2012 - Charlotte - More rain causes Erica Enders to get loose and lose round 1 against WJ, Shane Gray isn't nearly as lucky as his dad on a wet track and wrecks, and Dave Connolly and Vincent Nobile skate to the finish line in their round 2 race.
What do you make of it? Just bad luck? Coincidence? Is Pro Stock that finicky of a class? Does NHRA really not care about them as some others stated? How do you come to a solution to balance it all out. (Please no "they're just filler anyways" replies!

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Also of note, the Mountain View Dodge was represented in the 2009 Pomona, 2010 Phoenix, and 2012 Charlotte incidents. WJ was in the 2009 Atlanta, 2009 Reading, and 2010 Seattle incidents (and 2012 Charlotte as a beneficiary), Johnny Gray had 2009 Pomona and Atlanta, Shane Gray had 2010 Seattle and 2012 Charlotte, and V. Gaines was involved in the 2009 Pomona and 2010 Seattle incidents. Weird how that works out with the same guys.