As the Cleveland Cavaliers visit Boston on Sunday without former Celtics Isaiah Thomas and Jae Crowder, both dealt before Thursday's trade deadline, I think it's worth investigating how the Kyrie Irving trade went so wrong in Cleveland. Crowder and Thomas, the veterans acquired for Irving, along with rookie Ante Zizic and the Brooklyn Nets' 2018 first-round pick, lasted less than six unhappy months. I, too, believed the package was a good return for Irving, giving the Cavaliers a much better grade on the deal (A) than the Celtics (C) initially. Those evened up to some extent when I regraded after we learned Cleveland had greater concern about the condition of Thomas' injured hip, but the Cavaliers still came out ahead (A-minus vs. B-minus). So where did I go wrong? What happened to Crowder and Thomas? Hip injury limited Thomas' play A story by my former ESPN colleague Tom Haberstroh after the trade wisely raised the concern that other guards such as Michael Carter-Williams and Jonny Flynn had been less effective after hip labrum tears like Thomas' injury. Even compared to those cautionary examples, Thomas has been disappointing. His box plus-minus (BPM) metric on (minus-5.9 rating per 100 possessions, putting him among the league's bottom-10 regulars so far) is worse than Carter-Williams was last season after his hip surgery (minus-2.4). Thomas has been better than Flynn was in 2010-11 (minus-7.2), but then, Flynn was coming off an up-and-down rookie campaign, not one in which he made the All-NBA second team. In fact, if we switch to using player win percentage (the per-minute version of my wins above replacement player metric akin to BPM or PER), Thomas' decline is almost without precedent in modern NBA history. Last season, his .698 win percentage ranked 14th in the league, just behind Anthony Davis. That translated into more than 15 WARP. So far in 2017-18, Thomas' .395 win percentage puts him slightly below replacement level. Granting that Thomas' season isn't done yet, only one player since the ABA-NBA merger has seen his win percentage decline more from one year to the next.