So my new team is not very good, and I have one star player that still in his prime. But I'm beginning to realize that by the time I can get my team turned around (probably at least a couple years), he's going to be near or at the age where he starts to decline.

So my questions is, would you trade the player below for prospects if you had little to no chance of winning soon? And if so, what would be a reasonable haul to get back for him considering I need pretty much everything? Or is he not worth that much? Never done a trade before and I don't want to get fleeced.

http://www.whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=1226126

Lots of reasonable answers to this, but here's one to start - It seems very likely this guy will be Type A when he goes to FA meaning he might be worth as much as a low end 1st round pick and a supp pick to you (or whomever you trade him to). Using that as one perspective you could look at past drafts and see the type of players drafted between picks 17-50 (approx.) and say he's worth 2 guys like that.

(If you keep him, keep in mind you might only get the supp and a lower pick depending on circumstances, but I'd aim high since you have 2 seasons to max value)

You could also lay low and check the DL reports and strike when an owner really NEEDS a bat to relace an injured slugger.

He's a top-quality bat; I've been in worlds where he would be the best offensive player, although in most world he's not quite that good.

Don't rush to trade him. He may help you contend yet; he's likely to be productive for another 4-5 seasons or so. Move him only for a top prospect, if not one of the 5 best prospects in your world, then one of the 20 best.

If you're not sure enough about how to read ratings to determine the 20 best prospects in your world, find a mentor.

I'd trade him before that low health rating kicks in ... and it will eventually. Ask for one very good prospect or two good prospects.

To put it is perspective, I traded for Ralph Ramsey in Season 13 and gave up Hoss Serafini, Mark Shibata, and Lawrence Stankiewicz.

Ramsey is a bit better, but still comparable. Ramsey is (well... maybe "was" as he is starting to hit his decline and is losing his power) the top offensive player in the league and in fact won 2 straight MVPs after I traded for him. As you can see, I gave up a lot. Serafini was nothing special but was valuable because he was pre-arb when I traded him, so a starting-caliber player for cheap is somewhat valuable. Shibata was borderline-SS defensively with an .800 OPS and was an expiring Type A contract who the owner resigned. Stankiwicz was a weak defensive CF who couldn't play 2B (because he throws y) but has been good for .900+ OPS in the big leagues.

You won't get the same haul for McMahon because he only has 2 years on his deal (as opposed to 3 when I traded for Ramsey) and he's not quite as good. Just looking at his awards he has 2 Silver Sluggers and 1 All-Star, whereas Ramsey in an 8-time MVP, so I think even a top-20 prospect is unrealistic. He's probably not one of the 10 best current players in the league, so you aren't going to get the same return in prospects. If I'm giving up a top-20 prospect, I want a top-10 current player, because the current player is going to cost me 6M+ (or whatever his figure is) and I'll only have control for 2 or 3 years, whereas a prospect can be under your control for 10 years and 5 of them will be for cheap.

With that said, I would not be in a rush to trade that guy. Now that he's out of Petco, he should be good for .950+ OPS per season for the next 4-5. Look at his ratings, even when his power drops to 80-85, he's still going to be good for .900 OPS or so. He's not a 2B where he will become much less valuable when his range starts to go. DH's with good contact/eye and splits can hang around forever because those ratings slip slowly.

Very simple. If you want to trade him announce in the trade chat that you want to trade him and be patient. If someone fills up the world chat right away post it a second time.

Not everyone will make a trade offer within an hour or two of you posting so give it a day or two before you decide.

Also remember what my Dad always said. If someone tells you you need to move right away cause this is a limited time offer tell them sorry no deal. Fact is that the offer is probably only good for a limited time because they know if you think about it you will figure out how your being cheated.