Dick measuring contest aside, foam rolling is for myofascial release. It's a form of giving yourself a deep tissue massage, and yes, I'm painfully aware of how sexual this sounds when it's not remotely sexual. There's simply no words to describe it. I've never heard nor read claims of foam rolling being able to change the direction of muscle fibers or change their shape and or length.
I took it up on the recommendation from my GP, who went to Stanford if we want to continue this silly contest which I'm not a part of, thankfully. I'm not going to say I'm an old fogey, because I'm not, but it's certainly helped with what typical strain I experienced before doing it. It took several weeks before I noticed its impact. Strain you, as a man, would experience once you've passed your mid late thirties and aren't as limber.
It's done great things for my back. Also works great if you pull your back. A combination of tightness, heat and rolling alleviate a pulled back faster than sitting in bed or on the couch. GP recommending something called a rumble roller, but I don't fancy the look of them or the perceived pain-pleasure capability of them, akin to a human tenderizer.