I think there can be tremendous value in some trends, but will never base a play entirely on any particular trend.
I have a background in math and physics, and I've dealt with stats a lot in my years, which is also a big reason why I love sports so much (and incidentally betting them). If there's one thing I know about trying to derive any kind of meaning from a statistic or trend, and trying to use it to predict the future, it's that you MUST have a big enough sample size AND you must be able to back up WHY you think the trend will continue.
Regarding the trend above, 6 out of 7 looks pretty good, and I'm not saying that this trend doesn't have merit, but 7 is a very small sample size. Hell, 50 is a small sample size.
It is very difficult to find large sample sizes in football games because they only play 16 games and so many other variables change from year to year, or even game to game.
I will still take some trends into consideration though, but they are always just one factor in deciding a play, and only ever when I can back it up with reasons why I think that trend will continue.
Just because you flip a coin and it lands on heads 9 our of 10 times does not mean it has a 90% chance of hitting heads on the 11th try. BUT, if you think there is a valid reason why it hit heads 9 out of 10 times (external factors, weighted coin, sleight of hand, etc.), then maybe there is some value in the trend.
Scrapman, nobody does more research on this kind of stuff than you do and I always enjoy seeing the trends you come up with. Just want to caution anyone who relies heavily on trends, from a mathematical point of view, to look at other factors too and make sure the trend makes sense!