Elaborate a bit more on this. I'm not sure what you mean. Are you asking why a team would front load a contract instead of just paying an even or backloaded deal, investing the saved money from 2020 into something, and using the yield to cover the extra costs in future years?
If that is what you're saying, that is something I would have to think about. But it hasn't stopped teams from frontloading contracts before. Its not as common as backloading a deal, but with the extreme concerns surrounding that 4th year for Donaldson, it seems to make some sense that you'd want to pay as little as possible in those years where his value is a little more ambiguous.