I do not see how this would be vetoable. Not a great trade for the Lowell side, but it can make sense. Kendrick can't seem to stay on the field, and really only offers a good average with low/decent power and speed numbers. Lowell is coming off an ijury and is in his declining years. He offers some promise of going back to his productive years, which says possible .290 80 20-25 80.
yeah seriously man, i'd be throwing a fit here, as technically kendrick hasn't had an ohmygod season yet and to echo what dashiz says he hasn't had a full season, and whilst lowell is declining i suppose he's a pedestrian 3B in a pretty-deep to deep league, it's not like highway robbery really although lets just say i wouldn't be on the getting-lowell side, so maybe your commish is like me and shiz here thinking "dude if the guy wants lowell for kendrick take it and run" because i myself am spying kendrick in a few leagues where i'm iffy (kelly johnson-ish) at 2B thinking if i can land kendrick having a slightly-above-fantasy-average 2B to back him up means i'll take my shot at a .320+ hitter to make up for a power hitter who's well below .275 with power, example: this is a strategy i'm trying to work out in a league where i have adam dunn as my first basement.
in the immortal words of mirc, slap your commish with a trout and ask him why the fudge he done vetoed that trade because it's not ridiculously slanted, but seriously if someone wants to give you kendrick for lowell it is your civic duty as a good solid fantasy baseball player to take that trade and run with it
this might be a good time to make sure the wick on your torch is in working order, just in case your commish gives you some backlash. be sure to have the other guy plead his case too, cuz if he thinks he's getting something he needs and he's undervaluing howie-kay, that's his prerogative, bobby brown.
I've been in my fair share of leagues before that'll reject trades based solely on default rankings from Yahoo/ESPN/whatever site. Last year was the worst. Only ONE trade went through: Johan Santana for Johnny Cueto (probably cause it was between the 2 guys that were obviously vetoing more than anyone else). The worst part of it all was that since they kept vetoing my trades, I had to drop players cause they were eating up space in the bench, which included: Jacoby Ellsbury, Dustin Pedroia, Kevin Youkilis, Dan Uggla & Evan Longoria. Trades they rejected involving my team include: Andruw Jones for Josh Hamilton & Dice-BB for Cliff Lee. Sigh. Their reason would be "unproven", look where they are now on ADP.
Just venting. I know it's frustrating with a veto-happy league.