Since SoundCloud I am extra cautious with USV investments. They invest, pump (pulling other investors into their great opportunity) and then nothing.
Not every investment will succeed which is the point of risky startup investment. And USV has an incredible amount of success (Twitter, Kickstarter, Cloudflare etc)
SoundCloud? Just look at the recent downround.
The 'incredible auccess' is decades ago. USV had its best times.