There is no more significant expression of political power than the reshuffle. The disposition of the talent available is not relevant. A reshuffle is a public manifestation of what the party leader can do – and just as much, what they can’t.

So from the moment the first gossip of a Labour reshuffle appeared like a plump juicy cherry in time for the Christmas news drought, it became the only seasonal soap you needed to keep up with.

Like all the best parlour games, the rules of reshuffle are easy to grasp. They stay the same regardless of the politics of the party concerned. This is the conundrum: if x is offered y, will they a) go quietly but brief privately about their only loyalty being to the party (a faint, familiar lament heard in the bars and corridors of Westminster), b) resign and leave the frontbench entirely, creating a rival power base from which to prepare a potentially lethal attack (a threat made more often in theory than practice), or c) refuse to move and insist on being sacked or allowed to stay, also known as the Iain Duncan Smith approach.

Clearly in this scenario, only a) is anything like a victory for the leadership, although b) might be tolerable so long as the sackee’s high status was largely in their own imagination. Once c) is known to have happened, the minister or shadow minister concerned is on top. Think Gordon Brown, the unsackable chancellor.

Tony Blair with Gordon Brown in 2006. Photograph: Stephen Hird/Reuters

None of this matters a row of beans to a leader who feels the force is with them, or at least wants it to appear they feel the force is with them. But Corbyn’s only source of force is the people who voted for him last summer. They have no formal channel of communication with the leadership and certainly no formal say in who should be on Labour’s frontbench.

What really matters though is that Corbyn has no way of meeting their political demands beyond promising a “new kind of politics”. This he defines in his interests, particularly on foreign policy. That makes sacking the shadow ministers who disagree on major policy items a hard step not to take. All the same, he shouldn’t take it.

It is still within living memory that the shadow cabinet was once decided by vote of the PLP, a system that infuriated generations of leaders who were forced to accommodate views not their own.

It meant that Tony Blair’s first couple of years as prime minister were constrained by senior ministers with whom he had barely any point of contact. That meant he had to proceed more cautiously than he would have liked, but it also helped him build support for what he intended to do, and to accustom voters to the idea of doing it. Opposition is a source of strength and a wise leader should welcome it, not allow lieutenants to gossip about revenge reshuffles.

Corbyn knows all this. When he became an MP in 1983, the Labour party in the country was in revolt against the party in parliament: he has experienced at first hand the consequences of schism, the bitterness inside the party, and the lack of confidence that it engenders outside it.

He is living proof that this schism was never resolved. It’s in the promise to heal it in the interests of party members that Corbyn’s strength lies. But the grassroots no longer have the old structures that once existed to develop and decide policy, and the weight given to their views has long since been replaced by the weight given to the views of the people who vote in general elections.

There is no evidence yet that the new leadership has come up with a way of communicating transparently with the membership: inviting submissions of questions to the prime minister doesn’t cut it, any more than Twitter trends should decide matters of policy. There is talk of putting Corbynistas into some of the key positions on the national executive: that would do nothing but give a veneer of accountability to leadership fiat.

On the day, a reshuffle is a brutal thing that can seem to translate into strength. But they often also have subtle, unpredictable consequences. The wisest leader is often the most cautious.