Theo Walcott had an interesting game overall against Southampton, combining his attacking work with a very good defensive work ethic, something that we do not always see from him.
Starting on the right side in the 4-3-3 attacking system, he certainly tried to help Hector Bellerin today on the flank and was very aggressive, making a total of four fouls in the game.
He spent most of the first half, sticking to the wing and putting crosses in.
In the second half, he used a more flexible approach and played more centrally, constantly switching positions with Perez. This was probably done in order to see more of the ball. This also allowed Bellerin to go forward even more and attack from the flank.
Walcott made what could have been a key pass on the break to Ozil whose horrible first touch prevented him from getting a scoring opportunity, and he also made another pass to Sanchez late in the game but it was too high and powerful for the Chilean forward to make good use of it.
Overall, he did not see much of the ball with 13 passes completed out of 17 but his work rate was spot on and he was subbed on the 74th minute for Iwobi.