Arsenal manager Mikel Arteta left Theo Walcott ‘wondering why’ he did not choose to substitute Bukayo Saka during the Gunners’ 5-0 win over Crystal Palace on Saturday. The 22-year-old played the full 90 minutes in a Premier League fixture for the 12th time this season. Saka has also played into stoppage time in a further three matches this term. While Arteta has only elected to substitute the forward in the 89th minute in two matches, as well. Saka’s endless spells on the pitch also extend to cup competitions with 90-minute matches against Manchester City in the Community Shield and Liverpool …