David Smith and his company, Motorsports Analytics, is in the business of analyzing the many tons of Nascar performance data, and drawing conclusions about relative performance. He is the sabermetrics guru of American stock car racing. His analysis is consistently applied and quantitatively rigorous. That doesn't mean his insight is infallible, but his data-driven approach has credibility that is lacking in the Nascar media and internet discussion boards, IMO.
A centerpiece of his body of work is the PEER analysis... Production in Equal Equipment Rating. This attempts to measure driver performance independently of car, crew chief, and team. Although not without controversy, this analysis adds insight to casual observations from the couch, I believe. Martin Truex has generally rated as a quality driver in this analysis, although he dipped to #20 in 2014, his first year with Furniture Row Racing. So that adds some credibility to his #1 ranking after 30 races this year, the position he has held since last spring.
1 Martin Truex 3.690
2 Kyle Larson 3.414
3 Kyle Busch 3.328
4 Brad Keselowski 2.552
4 Denny Hamlin 2.552
6 Kevin Harvick 2.509
7 Joey Logano 2.466
8 Clint Bowyer 2.284
9 Chase Elliott 1.862
10 Erik Jones 1.810
11 Ryan Newman 1.802
12 Kurt Busch 1.612
13 Matt Kenseth 1.448
14 Daniel Suárez 1.379
15 Jamie McMurray 1.328
16 Jimmie Johnson 1.207
17 Aric Almirola 0.886
18 Ricky Stenhouse 0.871
19 David Ragan 0.655
20 AJ Allmendinger 0.638
20 Matt DiBenedetto 0.638
22 Dale Earnhardt, Jr. 0.509
23 Trevor Bayne 0.500
24 Chris Buescher 0.483