Why January transfers rarely solve anything

The mid-season window is where clubs go to fix a problem quickly, and where the evidence says they usually do not.

No pre-season, no patterns

A player joining in January misses the period when a squad's automatisms are built. They are asked to slot into patterns everyone else rehearsed for six weeks.

Signing a player in January buys you a footballer. It does not buy you a fit.

The exceptions tend to be players moving between similar systems, or those replacing a like-for-like injury rather than fixing a structural flaw.