By Neil Moxley Does anyone know if Erik ten Hag is a good football manager? Or if he’s just bang average? He’s fast approaching two years in the job and it’s difficult to gauge whether, if given the tools, he can turn Manchester United into a genuine force. On one hand, his first full season gathered pace like an Alpine avalanche after a horrible start, culminating in the Carabao Cup and a finish in the top four. On the other, his second has been limp. An awful Champions League campaign, stuttering return in the domestic league but still with a realistic shot at success in the FA Cup, it’s b…