He was far from inconsistent when compared to the average pitcher in MLB.
His injuries and suspensions are what made him unreliable, and some of his poor performances were partially a result of those injuries or rustiness upon returning from those injuries and the suspension.
I'll use ERA as my stat of choice, because it's easier to research. Wright started off slowly in the minors, and ended up with about the same ERA as his career MLB number (3.77 to 3.79).
His first 5 years were a bit "all over the map:"
5.67 (114 IP as a SP'er)
4.14 (148 as SP'er)
2.48 (87 almost all as RP'er)
4.91 (JUST 7 IP, so I don't count this)
5.02 (75 IP almost all as RP)
6.19 (134 back to mostly a SP'er)
Then, we see a lot of consistently good numbers from 2012-2018, except for injury or shortened seasons:
2.54 (142 all as SP'er/ traded to BOS in 2012)
4.26 (135 IP all as SP'er with 13 IP in MLB at 5.40)
3.42 (100 IP all as SP'er in 2014)
4.09 (73 IP with BOS as SP/RP) and 3.81 in AAA (52 IP all as SP) 2015
3.81 (157 IP with BOS aa in 24 starts)
8.25 (JUST 24 IP in 5 starts- injured most of 2017)
2.68 (54 IP mostly in relief in 2018) and 4.86 in just 17 IP at AAA.
If you throw out the 24 IP season of 2017, Wright had 6 straight seasons of remarkable consistency and positive production. His worst season was a decent 4.26 season way back in 2013.