The trade deadline has come and gone and there has been much analysis of each individual trade around the internet. I've decided to add my voice to the fray on a more macro scale, namely, to look at one way the teams that made these trades may have been evaluating players. A popular topic around the Oilogosphere is the dichotomy between "saw him good" scouting and scounting via evidence provided by statistical analysis. Jonathan Willis recently did a post on the Edmonton Oilers recent aquisition of Patrick O'Sullivan and speculated that one reason that the Oilers may have liked him is his particularly good play against the Oilers. O'Sullivan's boxcar numbers (goals, assists and points) were much better against the Oilers than his performance against the rest of the league. Is this significant? In an attempt to answer that question I looked at all of the NHL players who were traded at the deadline (with the exception of Erik Cole since his circumstances are quite unique) and compared their performance against the team that had acquired them with their performance against the rest of the league over the last two NHL seasons. I believe this is the same method that Jonathan used earlier. The following table is organized by the difference in the player's points per game between these two groups:
What can be concluded from this? First of all, a couple of caveats: these are all small sample sizes so teams shouldn't really be using these games to decide on the merits of a given player. Similarly, it may be difficult for us, as observers, to judge how much this data is getting used. In addition, not all of these players were obtained to play in an offensive role so these statistics probably aren't helpful for judging whether or not San Jose picked up Travis Moen because he played well against them.
With those caveats in mind these statistics look pretty random to me. On the whole I think it's doubtful that NHL teams as a whole prioritize these games in their overall evaluation. They may play a part, but I doubt that it's a dominant role. A good team to illustrate this is Phoenix who obtained a couple of players near the top of this list (Lombardi and Prust) and a couple of players near the bottom (Upshall and Dawes). Anaheim did this as well with their aquisitions of Wisniewski and Christensen. Other teams that made significant aquisitions fall anywhere from the bottom of the list (Moore, Morris), to the middle (Jokinen, Antropov) and of course to the top (O'Sullivan, Eminger). It's perhaps true that certain teams (like Edmonton or Florida) do depend heavily on how a player has performed against them in the past but I think it's more likely that O'Sullivan and Eminger's overperformance against their new teams is just the luck of the draw (some are bound to overperform and some underperform, especially given the small sample size).
This does not, of course, answer how much value is placed on statistical analysis and how much on first-hand scouting reports but it does hopefully provide some insight into how teams are evaluating players.