Kerfoot is a top notch PKer and was much better at ES last year. Rodrigues had a ton of PP time and still had fewer points overall than Kerfoot had ES points. Rodrigues is not a great defensive player and while he occasionally PK's, he is not trusted with full time opportunities there.
Rodrigues is a solid depth scorer coming off of a career year and his career year was mostly defined by a very impressive stretch of 30 points in the first half, but only 13 points in the second half.
That first half makes him an intriguing bet, and is the main reason why he got a 2 mill deal in the first place, but for much of his NHL career, his performances have been more similar to the latter half of last year. That is probably why he was not getting much interest. He is 29 and he has played like a league minimum player or worse for much of his career.
Kerfoot is closer to guys like Mikheyev and Lehkonen, who received 4 x 4.75 and 5 x 4.5 deals respectively, than he is to a guy like Rodrigues. For a long time, I could have signed Stastny, Kessel, Heinen, etc. for less than Rodrigues got and those guys could arguably put up more points than Rodrigues.
From Colorado's perspective though, they needed someone who could play middle 6 center. Rodrigues is far from the best option to do that, but he was really their only option short of trading for a guy like Kerfoot. Even if Newhook takes a major step forward, they will likely need to get a major piece at the TDL if they want to be competitive again.
Colorado would have been a good fit for Kerfoot, but there are still other teams and unless they really like Milano (who is a very different type of player), then nobody really comes close to bringing what Kerfoot brings to the table.