People are way more productive, focused, and determined when pairing. It's simply much harder to waste time and produce low quality work when you're directly accountable to the person next to you.
Scrum solves the urgency, commitment, follow-through, and slow problems. Each iteration the team has to commit to a set of tasks to get done. If they don't make it they have to figure out why they didn't, and how to improve. This continuous reflection and optimization is how team's get good and fast.
Of course there will be people who can't be brought into the team, but they are few and far between. And you can't tell until you've created a team for them to be brought in to. So instead of focusing so much on the fantasy of hiring a great team, learn how to build a great team.