Sam Warburton warns ‘we can only get better’ after Wales beat Scotland

• Jamie Roberts: ‘We had to dig very deep. The boys showed a lot of quality’• Warburton: ‘Scotland made it tough and don’t deserve to be zero for two’Sam Warburton issued a warning to Wales’s rivals in this year’s Six Nations when he stating that there was much more to come from him and his team-mates.The Cardiff Blue back-row told the BBC: “Historically we get better as the tournament goes on, which is a positive as we were slow out of the blocks last week [in the 16-16 draw in Dublin]. It was a much better performance this week.” Related: Wales’ George North scores try to ensure Six Nations …