Every year the non-waiver trading deadline generates fierce debate on the merits of a given trade. From talk show callers to prospect experts, everyone has an opinion on the winners and losers, the GM’s approach and the wider industry context on what’s being over or undervalued at that particular time.

Post-trade, however, most of the retrospective analysis is superficial and non-quantitative. Rarely do we see coverage of the longer term value differential of a particular trade, let alone the patterns of a particular GM over a period of time.

Curious then about what Theo Epstein’s return was against the trading costs, then, I ran the WAR numbers for the deadline trades made during his tenure. The list of traded parties was obtained from this excellent piece by Alex Speier.

The WAR calculations are derived from Fangraphs and counted the wins accumulated by players only for the teams involved in the transaction; Jason Bay, for example, is credited only for his WAR numbers with the Red Sox. His subsequent performance for the Mets is not considered. This analysis does not take into account the contract status of the players involved, importantly; Manny Ramirez’ entire tenure with the Dodgers, therefore, is considered.

It is also important to note that this is a snapshot; the longer term value of some of the traded assets – Nick Hagadone, for instance – is not yet determined and thus not part of these calculations. 2011 was omitted, in fact, because we have next to no data on the value contributed by either the pieces acquired or those traded.

With those caveats, here’s the data.

It may surprise some to learn that we have traded away approximately thirty wins (to date) in the last eight seasons. But it is actually the most probable outcome: even if we perfectly rate our prospects, we are – with rare exceptions such as last season – buyers at the deadline. Buyers, almost by definition, will be trading more value than they receive in return. The deadline represents the last time to acquire without restriction assets to improve your roster, and the marginal value of even fringe major leaguers can be magnified in tight races for a berth in the postseason. A half a win player could be, in fact, the difference.

This assertion is supported by the data. There is an obvious correlation between traded value and postseason performance; two of the top three years from a value traded perspective coincided with World Series wins. Half of the years where the net WAR total was non-negative, meanwhile, were years without a postseason appearance (2006, 2010).

The only thing that did surprise, ultimately, was the value of some of the players traded. His inability to get on base notwithstanding, Freddy Sanchez was, as Theo said, a pretty good player: he generated almost 12 wins for the Pirates during his time there. David Murphy, meanwhile, has been worth as much to Texas as Manny Ramirez was to the Dodgers, albeit in two more seasons. Erstwhile Red Sox reliever Joel Pineiro generated better than 6 wins for the Cardinals after leaving town, while Matt Murton was just shy of that number with the Cubs before heading for Japan. And so on.

Without comparing his performance to his peers – a task I don’t have time for at present, it’s difficult to quantitatively assess Epstein’s performance in context. And it’s true that it’s facile to point to the results – two World Series titles – because they may obscure fundamental flaws in the process.

But it’s worth observing that with rare exceptions like Justin Masterson (7.8 WAR and counting), the players Theo has resisted trading – but each of whom has been sought – are delivering much higher value than those that have departed.

All of which is a long winded way of saying that Epstein’s performance at the deadline seems more than adequate, the net 30 wins lost notwithstanding.

(Link to the source data I compiled in case anyone’s interested or wants to check it)