Jan.10 - Mercedes should have been braver and signed MotoGP legend Valentino Rossi for 2017.
"For me, Valentino was the most logical choice," Zanardi, a former Williams driver, told Italy's La Gazzetta dello Sport.
Mercedes has had to engineer a complex deal to get Bottas out of his 2017 Williams contract, involving Felipe Massa calling off his retirement and perhaps even fast-forwarding Paddy Lowe's move to Williams.
But Zanardi thinks Rossi, the 37-year-old flamboyant motorcycle racing star, would have been a more exciting choice to replace retiring world champion Nico Rosberg.
"I think it would have been perfect," he said. "His arrival in formula one would have boosted the audience a lot.
"Can you imagine the media impact that a single victory by Valentino at the wheel of a Mercedes would have had?" Zanardi, now a 50-year-old Paralympic hand-cycling champion, added.
But with Bottas set to be confirmed instead, Zanardi thinks Mercedes will again be strong in 2017 anyway.
He dismissed Ferrari's chances of a big improvement.
"I honestly do not think there will be a great improvement," said Zanardi. "I expect to see (Lewis) Hamilton win."