I think to answer your question is easiest to think of an analogy I heard from Justin Price once. SMR is kinda like part of the act of blowing a bubble. Before you can stretch the gum out and blow into to make the bubble you must chew it. Foam rolling can be thought of as the act of chewing. Without the chewing, the muscle cannot be stretchedout and used properly.
From a physiological standpoint, soft tissue (fascia, connective tisssue, muscle, etc) can lose its hydration if overused or nutrition is deficient, and adhesion can form. These adhesions are analogous to the little pockets of air that you may find in tge saran wrapping if you purchase meat at your market. These pockets essentially wont allow effective communication between brain and muscle to perform movement correctly, thus compensation occurs.
The compressive forces and slow (or no) rolling rate of the foam roller can help increase the hydration to the tissue. This begins to allow the filaments that allow muscle contractions to take place to slide easier. With that being said, foam rolling really is one part of a successful pre-workout plan.
Lets use a knee that “caves-in” during gait as an example for some pre-workout programming. A valgus knee us symptomatic of glutes that wont activate efficiently because of a length tension relationship at the hip. There is all kinds of stuff we need to do at the foot and ankle but for the upper leg, the glutes arent abke to do their job and the IT band is taking the brunt of the tension. A proper warmup to prepare for a walking or running workout would include using the foam roller to u n-tack the IT band and stretch the glutes so that they can handle the load of slowing down the knee.
YIKES! Thats a lot…hope it helps,