prior to 2013, their wide angle pro lenses were very average indeed, then it seems they wisely decided to give up on ultra-wide f/2.8 lenses and deliver superb f/4 lenses and thus came their superb
Canon EF 16-35mm f/4L IS and
Canon TS-E 17mm f/4L tilt shift lens and then this ultra-ultra-wide zoom lens to compete with the Sigma 12-24mm f/4.5-5.6 DG II HSM