LONDON — The cycle of sports can be brutally unforgiving.

Lionel Messi takes a couple of months off to mend a thigh injury, and he drops to being only the second-best player in his game. Manchester United enters a transitional phase after 26-plus years under the same management, and not only does the team fall from first to seventh in its domestic league, but the club’s stock price is down 17 percent from a high reached last May after United won its 20th league title.

Form is temporary. Maybe Messi and the owners of United are playing the longer game. The Argentine has one eye on trophies with Barcelona, the other on the 2014 World Cup for Argentina.

The Press Association on Monday drew a comment from United that the Glazer family, which owns United, “takes a long-term view about the share prices and the value of the club.”

That came after the shares fell this week to just above $15, compared with the $14 at which the club was floated in the summer of 2012.