Is the failure of England batsmen at test level an indication that county cricket's inferior quality?

Guys like Stoneman, Ballance, etc smoke runs at county level but can't do much against international bowlers. Yeah, their weaknesses are identified at international level, but so are the weaknesses of newcomers of other countries.

Is the quality of county cricket so low? There are a number of recent player from other countries like Australia who have "okay" records in their domestiv cricket but "great" record in county cricket. (Eg. Chris Rogers).