What I immediately see from this is that there's a whole lot more going on than just Baines to Schneiderlin to Walcott.
1. Sigurdsson has had set piece deliveries leading to three shots on target, and this is arguably the best position yet. Have to honor the right-foot delivery to the back post.
2. On that note, watch Keane at the back post making a run as if to head it back across goal.
3. Richarlison is just inside Keane, and Tosun is lurking from the penalty spot.
4. Baines continues a run across the edge of the box, where a return ball from Schneiderlin could be on.
5. One of the most impressive performances in this routine is Holgate. Seriously. He completely boxes out a Southampton player (Lemina, maybe?), and basically holds the entire wall for Schneiderlin to feed his pass into Walcott's feet.
6. Also of note, this has been rehearsed to a degree that Schneiderlin doesn't look at his pass. He instinctively knows what's going to happen, and that completely catches the defense out.
While this may not work quite the same way again, there are variations that could come off.
-A defender jumps into Walcott's path for the block, so he cuts back for Tosun.
-Schniederlin's ball is closed down, so he squares for Baines to shoot or pass through the gap. Even if he's not looking, Gana can help him make that call given his placement.
-Dummy the whole routine for Sigurdsson to deliver a ball to the back post.
-Add an extra motion, for Holgate to move across the gap and screen Walcott's defender. If they're man-marking, either Walcott comes free or Holgate drags his man to create space for someone in behind.
The hallmark of a good scripted play, to me, is its replicability and capacity for adjustments. This shows all of that.