QUOTE: “What does the pick value/slot money mean? Some estimate of value of the pick?”
Not exactly. Each spot in each round has a designated slot value under the rules. In total, a team can’t spend more than the sum of the values for all of the picks they sign (unless they want to incur a serious penalty). If they pay one guy more than slot, they have to pay others less – and vice versa. Slot for all picks after Round 10 is $100,000.
The reason some of the 10th rounders got such small bonuses is that teams took mediocre players and/or college seniors with no leverage who they could sign for almost no money – thus creating a larger pool to sign players where they needed extra money.
Note that it is a two-way street for college juniors. Yes, they have the option to return to school. But next year – as a senior with no leverage – they may well have to sign for a lot less than slot. Maybe for $5000. Mike Ahmed of Holy Cross was a 20th round pick his junior year and opted to sign – with that being one of the issues.