These are basically my thoughts too. Sarah Chalke is a good actress but she's just not Becky. By the time she joined the show, I think the writers really didn't know what to do with the character so I think she played Becky as well as she could. To be honest, I don't think they really knew what to do with the character of Becky after she and Mark got together. Her story lines in season 4 just kind of stagnated. Lecy, to me, is just Becky.