Kinell indeed. Cross-referencing to another thread on this forum, that's certainly one that's not only off the radar but also off the sonar and the spatial probe as well. Then again, summer and winter distributions are not too dissimilar to, say, Yellow-rumped Warbler (with a similar migration period?).
Considering its range, this one was certainly ON the radar of many people, along with future potentials like Swamp Sparrow, Olive-sided and Great Crested Flycatchers.