There have been a couple of players who have got some stick, but it's nothing compared to Wenger and Kroenke. Why Wenger seems reluctant to play on form players

There have been a couple of players who have got some stick, but it's nothing compared to Wenger and Kroenke. Why Wenger seems reluctant to play on form players and is reluctant/unwilling to buy another first class centre back and striker is beyond me.