The market for J.D. Martinez appeared to comprise just one team — the Boston Red Sox, who had the means, motive and opportunity to sign the outfielder/DH whom no other team seemed to come close to in terms of offers. That may have contributed to the lengthy stalemate. I think the Red Sox blinked, giving Martinez a five-year, $110 million deal that is certainly too long (the deal includes an opt-out after two years), but does improve their offense in a way no other free agent this year could have, and directly boosts their chances of repeating as division champs.
In the short term, Martinez is exactly what the Red Sox need: a power hitter to insert into a lineup that hit the fewest homers of any American League team last year — 168, 18 home runs behind the next lowest total. The Red Sox were fifth in the AL in OBP last year, helping them to a sixth-place finish in runs scored despite the lack of home run power, but with even average home run totals they likely would have finished in the top three.