Sweeney essentially is banking on the Bruins' system to get results. On paper, there can be no argument that E. Lindholm, Zadorov and Korpisalo have all been over-paid relative to their recent performance. In that sense I get the Athletic's methodology even though I think some of their grading is too harsh. But the GM is taking a calculated gamble with all 3 guys that in the right place, with the right people and teammates around them, they can all elevate their games, or perhaps in Lindholm's case simply get back to his best.
It's risk/reward, to varying degrees. Korpisalo is the biggest punt but the lowest cost if it goes wrong, the other two are much less of a stretch but have the potential to hurt more if they don't pan out. The Joonas deal in itself was unnecessary but putting that to one side, the general strategy is understandable - the Bruins' prospect pool is shallow and they refuse any sort of serious rebuild, which means playing pretty hard in the expensive and shaky waters of free agency to fill important gaps. In their situation, some over-spend and risk in doing so is just about unavoidable.