Donovan should be up top with Keane if he comes back, but he probably won't be. He'll probably play out-wide. So that leaves a gap Buddle would've filled, except he's been traded away.
Personally, I would like LA to not replace Buddle, as a 2nd striker, but instead go to a 4-2-1-3, with Donovan being the one, with Keane with Villarreal or Jimenez out wide, and have Zardes or McBean be the Center forwards. I think this better plays to LA's strengths, and would encourage a more fluid, attack oriented style, but this is just my dream. LA is going to run a 4-4-2, because that's what Arena likes, and how am I going to argue with the coach who won back to back championships playing that formation?
The options are Zardes, McBean, Villarreal and Magee.
I will exclude Villarreal, because he doesn't have the physique to be a forward in the MLS game, I see him as more of an attacking mid-fielder.
I include Magee, because he's a clinical finisher, and I think he's more suited to being a striker. I don't like him as a starter though. He's best suited as a sub, because of his versatility, and ability to score timely goals, but his skill level isn't as high as I would like a starter to be.
So that leaves Zardes and McBean.
They'll both probably see their fair share of time on the field early on in the season, but they will eventually have to decide who'll be the regular starter. Who should that be? That's tough, both have their merits.
McBean is a classic physical, hard working center forward. His strength is his ability to hold the ball up, and allowing his teammates more time to get into the attack. He'd help win and keep possession with his physicality. He makes a lot of runs, he's good with his head, and because of his physical strength he gets into good positions in the penalty box. He's what the Galaxy lacked at times last year with Donovan and Keane up top.
Zardes is a great athlete. He's 6-2, a great athlete, he's the top player in the college game, and he's gotten interest. That's basically what I hear. That's really all I have to go on to be honest, I'm not a scout, and I haven't seen anything from him, while I have watched quite a bit of McBean. From what people are saying I can infer what he'd bring. He'll add speed on the counter and with his size and athletic ability he'll be a force in the air. I've also read that he makes great runs, which could work nicely with Keane, and if he can pick out runners it would be an even better fit.
I'll be honest here, I have a bias towards McBean. For a couple of reasons.
1. Experience. McBean is younger, but he has more pro experience. He's been coached by LA's staff, in LA's system, and has practiced against LA's talent. Zardes has played as an amateur the past 3 years, while McBean has been a pro for the last 2.
2. I've seen it with McBean. I've see McBean dominate professional players in the CCL. That games against Isidro Metapan (I'm a soccer nerd, so I watched) was fantastic. It was on the road in central america, against a championship team's first squad (El Salvador champs). He had 3 goals total in the CCL group stage, which lead the Galaxy. Zardes has dominated, but he dominated amateur players, so we'll see.
Based off his experience and performances, in my opinion you'd have to give the edge to McBean, although that could change if Zardes comes in and lives up to the hype, but even then, McBean isn't a no name prospect, he's got a high ceiling and he's getting better and better , he's already getting interest from Scotland to ditch the USMNT.
McBean or Zardes is a good problem to have is the main point here.