That's an interesting construction. The top looks like it could start out like a top down shawl with a center st down the back and YOs on either side, but also with raglan shaping on the front of the sleeves as well. There would be 3 increase points rather than 4 as in a traditional raglan. Then you divide sts for sleeves like a raglan, the rest is just up to the stitch pattern and increasing so the sleeves and body flare out. Hmm.... gives me a couple ideas, not necessarily for a sweater like this though, just the construction.