Without knowing how mines work, I assume the D’Bringi have mined every jump point heading back towards their home systems so the Human fleets could be suffering some significant damage after each jump.
Also the D’Bringi have a bit of an emphasis on beam weapons, will that help them defending against a jump point assault?
Would the combined effects of the mines and beams be able to even out the tonnage difference?
It would be a reasonable assumption that the D'Bringi have mined all of the jumps heading back towards their home system. Certainly the humans would have to expect that, however, whether the D'Bringi have that many mines is another question. There is a hard to resist impulse to concentrate mines forward, at the point of contact, and the humans have no way of knowing at this point what the D'Bringi have done.
Mines are the only weapon in the game that attacks during the movement phase. Basically, if a ship or ships move into the same hex as a minefield, they are then attacked by a percentage of the mines present, based on the size of the ship. If the ships have long ranged scanners and point defense they can defend themselves fairly well, if they don't have long-range scanners then it is more difficult to mount a defense. If there are enough mines in the hex, then the minefield can easily destroy even large ships. Mines cannot be placed in the same hex as a warp point, unless it is a closed warp point, but they can be placed in the six hexes that surround a warp point, and commonly are.
The strategies for dealing with minefields typically involve saturating the minefield with enough targets to disperse its fire among numerous targets, and using minesweepers, which are ships with long-range scanners, enough point defense to deal with the maximum sized salvo for that class of ship, and then heavy armor and some beam weapons, which can sweep some of the remaining mines after they attack.
The D'Bringi fleet is primarily beam-armed, with some missile ships in support, which is the opposite of the human fleets, which are primarily missile armed, with some beam or other short or medium ranged ships in support. Coupled with mines it definitely could make a big difference. How much of a difference I don't know. Under the rules, approximately 30% of the defending fleet is active at the start of a warp point assault, and the defender has to roll to activate his ships going forward. This means that only a little bit less than one in three ships is ready to fire on the first turn. This is balanced out by the attacker's difficulties, primarily that he can only force so many ships through the warp point, and on the first turn of transit the newly arrived ships suffer heavy penalties to their to-hit rolls.
All of this adds up to a big fat "I don't know" what would happen if the humans assault the warp point, but I do know that it would be bloody and almost certainly they would suffer heavy losses. And the human fleet commanders know that too.
Kurt