It does seem to be more prevalent. As John points out - more strain as modern football is much quicker. I guess you only need to look at the use of new stats used where teams and players have distance covered during matches as a key indicator.
More needs to be done with regards to player screening now. It is becoming a regular occurrence and it's terrible to know he's leaving behind a wife 2 children and a 3rd on the way.
You'd have thought with medical screening these days it would be easy to screen for any underlying defects.
I think the stopping and starting is one of the keys as to why it seems so prevalent in football