Karl-Heinz Rummenigge has been quite vocal with his advocacy to shorten the summer transfer period and has recently come out and revealed that it's the so-called "smaller clubs" that are opposed to the change. While the Bayern CEO believes a shorter transfer window would benefit the whole of Europe, he insists that it's the smaller clubs that have been reluctant to make amendments to the timeframe.

Speaking to FC Bayern Munich magazine (via Goal.com), Rummenigge stated that an earlier deadline would bring much more of a unified sense of clarity across Europe's top leagues:

It must come to a uniform solution in the whole of Europe, independently on the start of the season in the individual leagues. A collective end of the transfer window on July 31st would also contribute to bringing more sense and rationality back to football. Such a useful solution would be in the sense of the clubs, all managers and fans if they knew on the first match day with which team their clubs start the new season.

The reluctance of 'smaller clubs' and Champions League implications, ramifications

Rummenigge was rather critical of Paris Saint-Germain for spending approximately €222m to acquire Neymar from Barcelona in this summer's transfer window, but also insisted that Bayern might not be too far off from a €100m transfer themselves, tweets ESPN FC Bayern Munich correspondent Mark Lovell:

Bayern did, in fact, break the Bundesliga transfer record fee bringing in Corentin Tolisso from Olympique Lyonnais this summer for around €41.5m, but that doesn't even break into the top ten list of the most expensive signings from the window. For Europe's elite clubs, Champions League football is quite often guaranteed and it gives an incredible amount of incentive for prospective players to pursue a move to said clubs (like Bayern). Where the issue really lays is with the smaller clubs who haven't secured group stage qualification in the Champions League before the close of the transfer window.

Rummenigge made sure to point out the fact that clubs on the fringe of Champions League qualification are usually the ones opposing a shorter transfer deadline to give themselves added time to adjust their squads:

I want to underline that an earlier end of the transfer window never failed due to the big European clubs, but to the smaller clubs which wanted to absorb a possible failure in the UCL qualification on the transfer market.

The financial ramifications of qualifying for the Champions League are massive for any club, but are much greater for the clubs who are on the periphery of the competition. This puts a lot more pressure on their summer transfer business on both sides of the coin for those clubs in both players sold, and players purchased. It also gives too much power to players who want to leave their current clubs — they can decide to leave if they don't secure qualification for European competition. Shortening the window could eliminate the power struggle between the club and the player.