Markus Rosenberg? Had a pretty good Euro u21s, finished as 4th top league scorer in the Bundesliga and then just looked remarkably average ever since. No goals in 33 appearances for West Brom.
Maceo Rigters was a very average player throughout his career but off the back of finishing top scorer in the Euro u21s (and scoring an overhead kick in the final?) he got a move to the Premier League. Made just two appearances for Blackburn despite being on their books for four years. In those four years he managed just 5 goals while out on loan at Willem II. Now apparently scoring goals for fun for Gold Coast United.
Probably a bit harsh but
Lucas Barrios looked excellent in the Dortmund team that won their first title in just under a decade. Linked with plenty of big clubs and looked to be an essential part of their fluid, dynamic football. Also got to the final of the Copa America with Paraguay. Moved to China, realised it was a terrible idea but had presumably already damaged his reputation in Europe enough so that the only top European clubs that were interested in him came from Russia, and he managed just 1 goal in his first season for Spartak Moscow. Seemingly out of the picture for the national team too.
Zvjezdan Misimović in his two seasons at Wolfsburg got more assists than Özil and I think is the only player in the Bundesliga record books that has gotten 20 assists in a single season. Him, Dzeko and Grafite were the trio that drove Wolfsburg to their only title in Bundesliga history and he was making a name for himself as a set-piece expert and incredibly productive creator. Went to Galatasaray and within three months he was moved into their reserve squad and he's now playing in China.
George Burley was actually excellent at Hearts and they were top of the league - ahead of both Rangers and Celtic - when he left the club.
Absolutely gash everywhere else he has been mind.
I remember him doing pretty well with a very mediocre Derby side just before Hearts as well, took them from 20th to 6th and got them playing some good football. Him and Billy Davies (Preston) came up against each other in the play-offs and were being hyped up as two of the best, most progressive British managers around.
Alan Dzagoev: One of the young stars of Euro 2012 and was subsequently highly sought after due to his performances in said competition. He didn't move however and remained at CSKA Moscow for six seasons thus far. From all that hype, he has subsequently gone completely off the radar of top clubs and you rarely his name crop up anymore.
Scored a
great goal against us back in 08/09 too. I think that was the game where Valencia hit the post with a cracking 25-yard strike in what must have been his only decent shot from outside the box in his United career.
Not sure it's fair to put Dzagoev up there simply because he's decided to stay in his home country until now - he's still just 23. There's every chance it's a personal decision for him to stay there rather than a reflection on his career progression/quality.