Manchester United are penny-pinching this January, trying to comply with Premier League spending rules after years of unwise investment. Financial Fair Play is in place for many reasons. Partly to try to ensure fair competition, and also to save clubs from themselves, amid poor ownership and bad short-term investments which can cause long-term havoc. Manchester United are constrained by spending rules right now, withThe Athletic reporting the club is not in a position to afford a permanent striker this month, not even £15 million Serhou Guirassy, unless player sales are completed. How did the …