To keep with the idea of simulating MLB the contracts are guarenteed and are not easily voided. Contracts, on the other hand, are common with team options with a buyout if declined. I think the buyout option is closest to actual MLB practices while also being most fair to owners who have been around for a while and responsible in giving contracts. It also keeps a level of accountability throughout the league while offering relief to bad contracts which at times are no fault if our own.