platitudes like "upright runners are bad" can be useful as guidelines...
if you don't have time to breakdown film on dozens of rookie candidates, and you hear a bunch of scouts saying this could be trouble for a given prospect, maybe where there is smoke there is fire...
but if you are making a more monumental decision with more fateful consequences for your team, and you are dealing for instance with a known commodity like LJ (hypothetically, should i blow up my team to get him for my dynasty squad if the price is right... or not?), they can cause more mischief than they are worth & ultimately lead to more confusion... it was ostensibly meant to alleviate (hate that when that happens)...
in that example (LJ) it would probably be worth it to take the time to look at him (or a player of that stature) on a case by case basis... it should be easier, too, becuase more data will exist on a veteran, more opportunity to have seen before, more access to highlights, to different opinions on player in question, etc...
imo, while LJ may be "more likely" to sustain an injury due to his upright & high contact style, he is a big, fast, tough dude, & has been fairly resilient in past two 1,700+ yard seasons... so maybe he is not as susceptible as some players that may also have run upright, but seem to have gotten hurt more (robert smith & chris brown come to mind)...
to recap, for brute force jobs (like an initial screen of a large number of relatively unknown & unproven rookies), concepts such as this floating around as "folk wisdom" can have value as mechanical heuristics... but for more precision work (you wouldn't want your watch repairman to use a sledgehammer), it can be a pretty crude, blunt instrument... that said, there are many jobs a sledgehammer is useful for... if i want to bust up a cinder block/cement wall, i don't want to use some tiny, specialized watch repair tool... the important thing is to have different tools, the ability to recognize what job is before you, & the flexibility & adaptibility to find the best fit & match for tool given the job...
in more important acts of judgement, involving more well known players, time permitting, it is probably best to bring our individual powers of observation & insight to the table...
even in doing that, with practice & through habit, you can build up an internal catalog, index, etc, of comp players that both FIT the more typical class or rule, & conversely, also those that are examples of EXCEPTIONS to the rule... these you could probably employ more "mechanically" (going forward, bringing them to bear on future analysis), but from a higher level & probably on surer ground & footing, as they will have been informed by your own thought (& dialogue such as we have here, with the 1,000-eyed monster that is the SP)...
this wasn't meant to come off as a pedantic logic exercize...
but imo this matter could be important enough to try & simplify & claify, & attempt to attack the problem on a more principled & fundamental level... even if the way suggested above is off base... ANY kind of debate which moves in the direction of trying to break this problem down, is bound to be useful to many...
good question...
* after re-reading your question, i didn't really respond to it... you were more asking is their staistical data to back up the premise that upright runners get hurt more often...
i was addressing my post to some (& i think there may be many... & maybe for good reason... the question about which your post addressed), that take the scouting maxim (upright runner = injury prone) as accepted wisdom...
& even if it is correct most of the time (i'll leave this as an open, unanswered question), it CAN'T be correct all the time... in case of dickerson, upright most definitely did NOT = bad... maybe it needn't for LJ, too... fred taylor is/was fragile freddie, yet i'm not sure if he runs upright, compared to more classical comp player cites... but the bottom line, he used to get hurt like clockwork... so independent of his running style, we can evaluate his injury-proneness (if that is even a word or useful category) ON ITS OWN TERMS... running style consideration should probably enter into our thought process when evaluating players, but as a component, and not dismissively, without first looking at the bigger picture...