So factoring in JUST mathematics you are talking about 6.25%, and that is only if you assign equal 25% odds to each team, and not believe that NYY has higher odds with Machado, and that Harper has higher odds with LAD, Cubs, or Nats.
At 6% we are talking 1 in 16 odds, meaning 15 out of 16 failures. Is the difference between 1 and 6% significant enough to really quibble over the odds not being very low? I'd say if I told you that 15 times out of 16 you would fail at something, the odds were very small of it happening.
Again that doesn't factor in that the first signing will probably be big enough to make the second large contract not worth it to the team payrolls of the future, or that the teams who miss out will run up the bidding past a Sox comfort point even if we signed the first one.