Another reason for the improvements in endovascular therapy outcomes is the use of better neuroimaging criteria for selection of endovascular therapy candidates.

Of course you get better results if you don't test the really bad candidates. So you as a stroke person need to make sure your stroke fits into the criteria for use of these medical devices. Heaven forbid that doctors and researchers actually come up with treatments for really bad cases.  You better hope you are a cherry pick candidate.
https://consultqd.clevelandclinic.org/2015/09/advanced-endovascular-therapy-for-acute-stroke-the-evidence-is-in/?

Progress in patient selection too

Another reason for the improvements in endovascular therapy outcomes is the use of better neuroimaging criteria for selection of endovascular therapy candidates.
Criteria in the latest studies are similar to those in the “hyperacute MRI protocol” used for the past several years by Cleveland Clinic’s Cerebrovascular Center. “This protocol promotes the use of advanced MRI techniques (in conjunction with CT or CT angiography) to enable more precise determination of tissue viability and occlusion impact before acute stroke intervention,” says Cerebrovascular Center specialist Gabor Toth, MD. This has allowed Cleveland Clinic stroke specialists to better select patients within traditional time windows for intra-arterial stroke therapy and to extend the window for acute interventional treatment.