A lead-generation site is typically paid per referral by the agent it sends you to, which means the match is driven by who paid for the lead, not by who has the strongest recent sales record in your specific neighbourhood or price range.
That does not make every agent from a lead form a bad choice, but it means you should do the same homework you would for any agent: ask for 3 to 5 comparable sales they have closed nearby, and confirm their licence is active and in good standing before signing a representation agreement.
A referral source is not a credential. The agent's actual local track record is. Get your hand-reviewed valuation from Joel Dyck.