This will be an unpopular opinion, but I don't like the move.
His cap hit this was supposed to be $11,294,000 and cutting him will result in $5,082,000 dead cap space. The net savings is $6,212,000.
That's decent savings, but it also forces a rookie into action early while limiting the depth.
To be clear, I'm not saying Leno is better, but for what they got being ~$6.2M in cap space they are now rushing the development of Jenkins and making the team more vulnerable to injury.
I'm always against rushing a rookie into playing. I think for their own confidence it's best for them to start once they have won the job. As bad as Leno has been, without training camp it seems way too early to say a 2nd rounder is a starter.