That's why he was a 7th round draft pick. He's a subpar athlete.
His low draft status definitely wan't because he lacked production. PFF ranked him very high because he was extremely productive in college.
Sometimes players have other things that make up for their athletic deficiencies. Did you know Michael Bennet ran a 5.13 40 at the Combine and went undrafted?
That's very slow too. But he makes up for it with other qualities.
Lawler plays with good power, a low pad level, very good technique. He generated a lot of pressure in college.
In the NFL, he may not get to the QB, but if he wins his blocks and creates pressure, that's valuable.