So why did the Kings sign him? Hollins is essentially an experienced version of Eric Moreland, someone who can bring that type of skillset but also can come in and play right away. Hollins signing probably means Moreland is even further out of the rotation than he already was.
Over his career Ryan Hollins has been a solid, if not spectacular shotblocker. His career block rate of 3.4% is above average, but hardly elite. That number isn't super reflective of his overall impact however, as last year his block rate was a very good 4.9%. For comparison, DeMarcus Cousins had a block rate of 3.2% last year. Hollins length allows him to be a very good rim protector. According to NBA.com, opponent FG% at the rim against Hollins was a paltry 36.6% last year, the best of any player to play at least 60 games and average 0.5 blocks a game. Mind you, that came in only 8 minutes a game, likely against opposing backups, but it's still a fantastic number.
Hollins is not a very good rebounder for his size however, with only a 12.5% career defensive rebound rate. All in all, he's the worst rebounding big man on the Kings roster already, on par with a Rudy Gay or Derrick Williams. Fortunately for Hollins the Kings are a very good rebounding team thanks to DeMarcus Cousins and Reggie Evans, two of the best rebounders in the league.
Offensively, Hollins is limited to right around the basket, but he's judicious and efficient with his touches. Hollins has a career FG% of 57.6% and both his last two seasons with the Clippers featured him shooting over 60% from the field (being on a team with Chris Paul and a bunch of other weapons likely helped). 30 of Hollins' 72 FGA last year were dunks, of which he only missed one.
He's athletic enough that he could play next to DeMarcus Cousins at times or any of our other big men and he's well suited in playing a fast pace as the Kings seemingly want to do. He isn't an exciting signing but he's a useful veteran who fills a couple needs for the Kings without being too expensive.