imo it's just Portland. The order in which the decision tree is written (eye v control first, then hitting split v pitching split), in conjunction with Portland also being -4 for singles, renders him almost completely useless. His isolated discipline of .100+ is quite good, but his isolated power of .130-.160 is super-low for a power attribute of 92. Portland's park factors are -3 for doubles, -4 for triples, and -2-2 for home runs, which devastates his slugging percentage. You're losing batting average as a whole, and slugging percentage on the hits he's actually getting. Extreme parks sorta break the game. Portland substantially exaggerates the badness of his vR. If you played in somewhere like Tucson (+3+3+4+3+3) he'd obviously be much better, or even somewhere reasonable like Louisville (+2+1+1+2+1). In Tucson he would hit ~.270+ and his isolated power would double. But obviously so would your pitchers' ERA so is it worth cutting off your nose to spite your face, as they say?
The stats actually imply otherwise--- At home he is actually a very reasonable .257/.361/.381 overall (105AB) compared to away he is .184/.284/.320 overall (147AB), but vRHP overall (170AB) he is .165/.260/.253 compared to vLHP overall (82AB) he is .317/.423/.537. We're still looking at extremely small sample sizes for each of these splits, so my guess is that over time R/L will regress towards one another where R is more like .190 and L is more like .280, and home/away will regress towards one another where home is more like ~.210 and away is more like ~.245. Seems super unlucky that his production away is so ridiculously bad, unless your league also has every other terrible pitching park like Seattle and Burlington etc etc and also has every other pitcher who is a vR Terminator. Give it time I guess