I'm not sure that I know what Grant is talking about. There some changes to the optmizer, as described in Books Online:

Query plans

SQL Server 2014 includes substantial improvements to the component that creates and optimized query plans. To take advantage of these improvements new database applications should be developed using database compatibility level 120. Applications that are migrated from earlier versions of SQL Server should be carefully tested to confirm that good performance is maintained or improved. For more information, see ALTER DATABASE Compatibility Level (Transact-SQL).

I have not found further description to what these changes are, but I don't know think it's related to how statistics are generated.