the word "revise"
For some job seekers, August was not a good month. Hiring fell to the slowest pace in eight months, and the previous estimate for June was revised lower by 28,000 jobs.
But if financial markets were worried, it didn’t show.
Should I put a comma between "revised" and "lower by"? And how to analyse the grammar of "and the previous estimate for June was revised lower by 28,000 jobs"? What does "were worried" in this context?