The fears of Dortmund fans everywhere are being realized as BVB and Bayern Munich are actively discussing a transfer for Mats Hummels. Bayern chairman Karl-Heinz Rummenigge confirmed the news on Tuesday morning as his side prepared to travel to Madrid for their Champions League tie with Atletico.

Karl-Heinz Rummenigge confirms that Bayern are in talks with Dortmund over signing Mats Hummels. #bvb #fcb — Marcus Christenson (@m_christenson) April 26, 2016

Hummels, who has captained Dortmund since 2014, came through the youth academy at Bayern. His only senior appearance for the Bavarians came in their final game of the 2007 season. In 2008 Mats was loaned to Dortmund and immediately had success partnering with Neven Subotic in the first team. The next year he was signed permanently by Jurgen Klopp.

To date the 27-year-old center-back has made 219 appearances for BVB in all competitions, scoring 19 goals. He also has 46 caps for the German senior team.

He's still under contract with Dortmund until next summer, so a transfer fee with Bayern will have to be arranged. But with Hummels clearly wanting to move to Munich, BVB won't have much incentive to hold out for a big transfer fee.

When Mats is at his best he is one of the best ball-playing defenders on the planet and can even contribute creatively going forward in attack. Overall, he's has had a very good season, but there have been a few moments of insanity.

His defensive mistakes in the second leg against Liverpool were a crucial part of Dortmund's fall out of the Europa League. His disallowed own goal against Ingolstadt in January was an inexplicable, and kind of hilarious, error that was luckily wiped out by a questionable foul call from the official.

Earlier today in the Bundesliga, Dortmund's Mats Hummels scored the own goal of the year. But it didn't count!! https://t.co/P0Lc83v9eb — FOX Soccer (@FOXSoccer) January 30, 2016

This departure will leave a big hole in Dortmund's back line, assuming that Subotic is also off this summer. Thomas Tuchel will certainly be in the market for a big defender to pair with Sokratis and to replace the 6'3 Hummels.

Much of the frustration here is that the Dortmund to Bayern player-pipeline still somehow exists. Apparently Hummels is enticed by Bayern's higher seeding in the Champions League and a bigger contract, but it still hurts that he would leave for one of our biggest rivals.

That's not exactly the behavior you expect out of a captain. But if he's not 100% committed to the cause, then it's best we find another Captain anyway.

How do you feel about Hummels assuming this move goes through? Do you understand his reasoning in wanting to go back to his boyhood club, or is this something you cannot forgive?