You really have to have solid, engaged recruiting and screening processes in place to filter the wheat from the chaff with H1B's.
I would interview 10 H1B's, and then one domestic candidate, and the domestic candidate would outperform every time.
This is obv anecdotal, but I would not be surprised if this pattern exists across the entire H1B pool.
We do hire some H1B's, and there are some incredibly talented candidates, but only after great expense and time invested in screening and interviewing.