Why was Axel Disasi's match-winning goal vs Villa cancelled?

Chelsea may be feeling hard done by after their comeback win over Aston Villa was denied by a VAR check.

It looks like the reason was Benoit Badiashile's slight shove on a Villa player seconds before the decisive header by Axel Disasi.

The explanation did not satisfy Mauricio Pochettino who was caught on camera saying 'What the f*** is this?'