From a results perspective they have been very succesful in result years, regularly been high in both the youth league and cup competitions.
They have also had several players who have done well with the England junior teams - for instance when Ledson and Kenny were part of the team U17 team that won the Euros Chelsea plauers Izzy Brown and Dominic Solanke were important parts of that success.
Indeed Mourinho himself said this in July 2014
http://www.dailymail.co.uk/sport/fo...minic-Solanke-dont-play-England-blame-ME.html
"Jose Mourinho has promised to deliver a bright future for the England national team and insists if three of his young talents at Chelsea don't make it, he will be to blame. The Blues boss has earmarked young talents Lewis Baker, Izzy Brown and Dominic Solanke as future England internationals, and is showing his faith in all three on tour across Europe with the first team. And with all three set to work with the senior players during the coming season, Mourinho is putting his neck on the line by promising FA Chairman Greg Dyke that all three will be full internationals in years to come."
Of the three, only Izzy Brown has a senior appearance for Chelsea - 11 mins in a dead rubber against West Brom at the end of last season.