Did Ian McShane always do good work, or did he go straight from Lovejoy to being in every Prime/Netflix/HBO show? Seems odd.
He was great as Lovejoy but i guess his versatility was probably sub-consciously questioned because he made such a convincing cheeky chappie. A bit like when Hugh Laurie went from doing Black Adder to House and The Night Manager. Americans instantly took to him as those serious characters but for us Brits it took a while to get his previous characters out of your mind before you could appreciate how good he was as the new ones. Bit of a long-winded way of saying 'yes' really 
He'd been acting for over 20 years before he did Lovejoy, although Lovejoy was his first "major" role, with any longevity. Lovejoy made him a household name, which allowed him to break into s**** US TV. Then he worked for almost another 20 years before he got 'Deadwood'.
Gotta hand it to him, he's a grafter, and probably deserves his success.