Martin Samuel can't understand why Chelsea have given Manchester United "a way back in" by selling them Juan Mata.
The Spain international signed a club record £37.1million deal on Saturday after being frozen out of Jose Mourinho's first-team plans at Stamford Bridge and the deal provides a boost to David Moyes in a difficult first season in charge.
The reigning champions have been knocked out of both domestic cups and currently sit seventh in the Premier League table, 14 points behind leaders Arsenal - but Samuel says the signing of Mata sends out a lot of positive messages for the club.
And the Daily Mail journalist cannot believe Chelsea given their fallen Premier League rivals such a boost.
"It's strange business from Chelsea's point of view," he told the Sunday Supplement.
"I can see the financial argument for it, but to do it now has left Manchester United with a way back in that I'm not sure they had before.
"It's what it does in terms of making it the place to be. Other players will be looking at that and thinking 'they've got Juan Mata'.
"It's what it says about the Glazers' readiness to invest as well because everyone was looking at that and thinking 'have they got the desire to invest in the team?' They've gone out and broken Manchester United's transfer record, so straight away, yes, they have got the desire to invest in the team.
"It's the messages that it has sent out and I cannot understand for the life of me why Chelsea would want to facilitate that."
Mata had won Chelsea's player of the year award in each of the last two seasons, but the returning Mourinho has preferred to play the likes of Eden Hazard, Oscar and Willian this season.
The 25-year-old has played the full 90 minutes in just two Premier League games this term and while Samuel can't believe they have sold him to a domestic rival, he accepts it is good business for the club.
"Obviously there is a financial aspect to it," he added.
"Juan Mata wasn't going to get in the team and that is now perfectly clear. The time of Jose looking at it and considering him as an option had gone. He was a reserve at best.
"I can see from Chelsea's point of view that they are looking at this as a moment in time. They can get £37million or £40million - or whatever figure everybody eventually settles on - for Juan Mata now.
"In the summer after five months in the reserves he probably wouldn't get in the Spanish World Cup squad as a result of that and his value would be possibly halved.
"So I can totally understand the financial imperative, I just can't understand why you'd want to give Manchester United a break."