A very brief lawyer's answer? It's by no means clear cut.
;)
OK, so that's what all lawyers say. The slightly longer analysis:
* The club may have been in repudiatory breach of the players' employment contracts when it failed to pay them on time. On a very simplistic level, the essence of any contract of employment is that I work for you, and you pay me. If you don't pay me, that is a fundamental breach of contract on your part.
* A key essence of repudiation is that the "victim" then has a choice: either to accept the repudiation and thereby terminate the contract; or to affirm the contract (thereby "rejecting" the opportunity to repudiate) and sue for damages.
* In this situation, the "pure contract" analysis may be that by staying on at the club, the players affirmed their contracts; they therefore lost the opportunity to repudiate and must therefore sue for damages. Their damages may be lost interest on any savings they have, or the cost of any penalties they had to pay (e.g. on mortgage / credit card payments).
* However, that is a "pure contract" analysis. Footballers' employment contracts will be subject to different rules concerning employment law, and there may even be some precedent concerning the peculiarities of footballers' contracts. I'm not an expert on either, so couldn't begin to advise on the players' rights.
* * *
From a pure contractual analysis - and subject, of course, to any overriding employment / football law issues - by staying on at the club, continuing to play, and then accepting their wages (albeit late), it is likelier than not that the players will be found to have affirmed, and therefore to have lost the right to repudiate, their contracts. They therefore simply have a right to claim for damages (provided they can establish that the club is in repudiatory breach - which, if the stories about non-payment of wages are to be believed, it may be). If the players then walked away from their contracts, it is they - rather than the club - who would be in repudiatory breach. The club could accept that repudiation - especially so in the close season - and then sue them for damages. The players ought to think long and hard before taking such a course of action.
As a footnote - the fact that the club paid the players late further muddies the water. Whether the club has remedied the repudiatory breach - or whether time is of the essence in respect of payment (and thus the late payment does not cure the earlier repudiatory breach) - is by no means clear. That said, the fact of the players staying on and then accepting those wages would point strongly towards affirmation.
Matt