The year he made the Pro Bowl, he had a team-high 142 total tackles, which was tied for seventh-most in the league. He had more solo tackles than all but three of the players ahead of him. He also had nine pass breakups and 2.5 sacks. Only two of the players who had more tackles than him had more sacks. Yet, he's obviously sucked every year.
In 2018, which I feel was his best year from an eyeball standpoint, he had 121 total tackles, which tied him for 13th in the league, but added four sacks, which was better than all but two of the players ahead of him in tackles. That was the year Vander Esch had 140 tackles to finish third in the league. Smith also forced two fumbles that year, recovered two and scored a TD, so maybe that colored my perception that 2018 was a better year. (He forced two and recovered one in 2019.)
Now, to be fair, he finished with 154 tackles last year playing virtually every snap and was third in the league, but we know that he struggled getting to his lane as the defenders in front of him failed to hold up blockers and he was making plays downfield instead of in the backfield or around the line of scrimmage ... although he only had one fewer tackle for loss (5) than he did in each of the previous two seasons. (For comparison, Darius Leonard had 7 tackles for loss each of the last two seasons after 12 as a rookie.)