It's interesting to look at some of these guys numbers and see who's improving / declining defensively.
John Wall in 2013-14 had a DRPM of -0.44 which was only good for 26th among all PG's. This year he improved to +1.73 and jumped to 3rd spot. That has got tone be among one of the greatest defensive improvements I've ever seen. When you combine that with his offensive improvements (averaging 10+ APG) that immediately catapults him among the top 2 or 3 Point Guards in the NBA i think.
On the other hand Marc Gasol in 2013-14 ranked first among centers (and 4th in the entire league) with a DRPM of +5.23 - but then this season his DRPM of +1.92 ranks him only 19th among centers and only 4 spots above Kelly Olynyk.
Speaking of Olynyk, in 2013-14 he had a DRPM of -1.71 which ranked him 62nd (4th last) among all NBA Centers. This year he's literally flipped that around with a +1.71 that ranks him 23rd in the league - that is an amazing improvement for a guy with such limited physical tools in only his second season. Wow!
Some other results:
* Zeller has stayed the same essentially going form 1.49 (33rd) to +1.37 (32nd).
* Sully has gotten much worse, dropping from +1.58 (23rd) to +0.16 (53rd)
* Crowder has gotten worse, dropping from +1.81 (13th) to -1.07 (52nd) this season
* Turner has improved modestly, from -1.28 (46th) to -0.27 (32nd)
* Bass slightly improved, from -0.43 (55th) to -0.19 (60th)
* Phil Pressey stayed similar, from -1.17 (35th) to
* Bradley, as mentioned, has dropped from +1.22 (6th) to +0.73 (12th)
* Isaiah Thomas has droppd from -1.62 (42nd) to -2.67 (67th)
Just for fun, the 5 best at each position...
Point Guard
1st: Ricky Rubio (+2.33)
2nd: Eric Bledsoe (+1.86)
3rd: John Wall (+1.73)
4th: Stephen Curry (+1.69)
5th: Kyle Lowry (+1.25)
Honourable mention: Marcus Smart (+1.07, 6th - big contrast to Wiggins)
Shooting Guard
1st: Khris Middleton (+4.10) - wow!
2nd: Nick Calathes (+3.75)
3rd: Elijah Millsap (+3.42)
4th: Andre Roberson (+3.30)
5th: Wesley Matthews (+2.27)
Honourable mention: Kyle Korver (+1.38, 10th - totally unexpected)
Small Forward
1st: Draymond Green (+5.24)
2nd: Tony Allen (+4.94)
3rd: Kawhi Leonard (+4.60)
4th: Michael Kidd-Gilchrist (+3.63)
5th: Thabo Sefolosha (+2.92)
Honourable mention: Gordon Hayward (+1.20, 14th - didn't expect him to be this solid)
Power Forward
1st: Tim Duncan (+4.69)
2nd: Anthony Davis (+4.20)
3rd: Darrell Arthur (+3.92)
4th: Serge Ibaka (+3.52)
5th: Cody Zeller (+3.23)
Honourable mention: Kevin Garnett (+2.31, 10th - still gettin' it done!)
Center
1st: Andrew Bogut (+5.50)
2nd: DeMarcus Cousins (+4.71)
3rd: Jusaf Nurkic (+4.00)
4th: Rudy Gobert (+3.62)
5th: Tyson Chandler (+3.55)
Honourable mention: Nerlens Noel (+3.36, 7th - lot of upside here)
The 5 worst at each position:
Point Guard
80th: Alex Shved (-2.97)
81st: Jordan Clarkson (-3.01)
82nd: D.J. Augustin (-3.23)
83rd: Tony Parker (-3.32)
84th: Zach Levine (-4.35)
Dis-Honourable mention: James Young (-2.06, 80th)
Shooting Guard
97th: Joe Harris (-3.49)
98th: Tony Wroten (-3.85)
99th: Bojan Bogdanovic (-3.91)
100th: Jamal Crawford (-4.15)
101st: Jabari Brown (-4.23)
Dis-Honourable mention: James Young (-2.06, 80th)
Small Forward
82nd: Jabari Parker (-2.65)
83rd: Martell Webster (-2.89)
84th: Marco Belinelli (-3.12)
85th: James Jones (-3.36)
86th: Terrence Ross (-3.77)
Dis-Honourable Mention: Rudy Gay (-2.46, 80th)
[Wiggins, Jeff Green, Carmelo Anthony all -2.00 or worse)
Power Forward
91st: Adreian Payne (-3.09)
92nd: Anthony Bennett (-3.23)
93rd: Jason Smith (-3.36)
94th: Ryan Anderson (-3.78)
95th: Derrick Williams (-4.58)
Dis-Honourable mention: Dirk Nowitzki (-1.89, 85th)
Center
69th: Jordan Hill (-1.41)
70th: Marreese Spreights (-1.51)
71st: Matt Bonner (-2.51)
72nd: Andrea Bargnani (-3.56)
73rd: Enes Kanter (-3.88)
Dis-Honourable mention: Anderson Varejao (-0.57, 61st)
Sadly Isaiah Thomas is statistically the 34th worst defensive-impact player in the NBA with a rank of 441/474, and by far the worst defensive player on this Celtics roster. Fortunately for him he's also statistically he 12th best offensive-impact player (+4.10) which means his net impact is still positive.