Because of cap spaces for each slot are bigger earlier. This Sox pick has a slot value of 375k. Sign him for $10k that is $365k, left over they can use later. The Sox pick in the 10th round is for $185k, so the same senior signing for 10k only saves $175k. By making this pick they generate $200,000 extra dollars they can use later. Once you get past round 10 there are no rewards for coming in under the slot value, which is $125k, but they will penalize you for anything over that number.