The 26-year-old centre has played just twice so far this term, with a thigh injury keeping him on the sidelines for the opening weeks of the Guinness PRO12.
But having reunited his exciting partnership with Bundee Aki, Lam believes Ronaldson could hold the key to Connacht's fortunes, with competition for places hotting up in the centres.
"Craig offers something totally different to the midfield," Lam said. "That's what you want.
"You've got Bundee, who is Bundee. You got Peter Robb, who is pretty abrasive and hardly makes errors. Craig brings a kicking game and has a lot of experience at outhalf and you got a left foot there too.
"You've Eoin Griffin who has a really good passing game, and Rory Parata.
"So there is good competition in that midfield now, an area where people thought would be difficult when Robbie [Henshaw] left."
Guinness PRO12 Connacht News
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