Don't get fooled by the David Silva hype - he is a wildly inconsistent player. Sterling has more goals and more assists than Silva in the last 2 years. Silva is on £200k per week and people are moaning that Sterling wants £100k+. If you look at the stats, his so-called demands aren't that unreasonable.
No he has not.
Silva in EPL:
2014-2015: 11 goals and 6 assists
2013-2014: 7 goals and 12 assists
2012-2013: 4 goals and 12 assists
2011-2012: 6 goals and 17 assists
2010-2011: 4 goals and 9 assists
Sterling in EPL:
2014-2015: 6 goals and 10 assists
2013-2014: 9 goals and 7 assists
2012-2013: 2 goals and 6 assists