Welcome to the cafe, dude! For future reference, I'd go through the extra-typing of listing your whole damn team cuz that way it's easier for us advice-dispensers to give you the best advice on your draft trade keeper and waivers questions going forward. I don't know what the rest of your team looks like, so it's hard to make a 100% for-sure opinion on it when I don't know what your other options are.
THAT SAID: i think joe mauer is overrated. everybody fell in love with his .320+/28/96 type season in 2009 and rightfully so, that was amazing production from the catcher position that nobody else is likely to re-create... whether it's the new ballpark and/or some sort of combination of mauer coming back to earth, last year he fell back to the more-typical .320/7/80 type #s that you'd get from mauer. he's not your prototypical masher, as he's more of a batting average type.
brian mccann, for me, is the floor of where i like my ideal catching stats to be. mccann had an off year last year and was like .270/20/75 or something, which isn't OMFG GET PAUL REVERE READY TO MAKE A MIDNIGHT RIDE type production, but it's a nice failsafe to have at catcher when you know that you're going to at least be more productive than, say, 75-80% of the league at C. personally, given relative draft positions, i'd go with mccann ahead of mauer... that's not to say that mauer isn't a better overall pure hitter who certainly has the potential to give you better #s, but like, for the buzz associated with his name and the cost of where you have to select him in a draft in order to have him, he's just not worth it IMO. it remains to be seen if he can pull a david wright of his arse and have a WTF?!?!?! power year in the first year of his new park and then turn around and regain most of the power the next season, but unlike david lee mauer isn't coming from multiple years of .300/30/100 type seasons... he's had one ~.320+/28/96 type season and then promptly turned back into the guy he was before the season. so while it's never a bad thing to have mauer, i don't think he's anything close to an untouchable asset at the C position.
brandon phillips had a down year last year... he's turning 30 years old this june. odds are that cincy's offense is going to get rolling with drew stubbs emerging alongside joey votto and jay bruce, who finally figured out how to hit .280 but has yet to do it with all of the power that tantalized us back when he'd hit .220. a down year for brandon phillips is evidenced by last year, .275/18/59/16, which was good for #87 overall in standard 5x5 roto baseball.
robinson cano is everyone's man crush... he's universally ranked as the #1 2B in the game and last year's .319/29/109 with 103 runs was good for #11 overall. 2009's .320/25/85 with the same 103 runs was good for #34 overall. cano is also roughly 1.5 years younger than brandon phillips... so basically, the cost of downgrading robbie cano to brandon phillips is your currency for this trade.
i always consider carl crawford to be a steals guy... granted he's been the king of the steals guys over the last few years, as he'll hit you 15+ HRs drive in 75+ runs while swiping you 40+ bags, but he's going to have an adjustment season this year. i wouldn't look too much into his #7 batting order place the other night, as francona is just tinkering around with his new toy. as it's been said, i wouldn't bet on another 18-20 HR season, figuring something like 10-15 would be his tops. saying that you're quite good in steals with cameron maybin, denard span, and erick aybar also is worth a chuckle, as i personally wouldn't trust any of them. if you also had juan pierre, brett garner, jacoby ellsbury, or rajai davis or people like that then i'd be more prone to believe you.
obviously, your trade partner wants robinson cano.... i think as it stands cano is a better pure power hitter than brandon phillips, and his pedigree shows that he's very likely to be a top-3 overall 2B in the game, with his upside being that of a top-10 player. hence why he's a first round draft pick.
you say that you want power, so i think giving up cano for brandon phillips and carl crawford isn't the move to make. if you wanted to say "i'm going to get teh best stolen base guy i can get and he'll also give me some solid power stats along with the steals" then sure i could see this trade, cuz IMO carl crawford bridges the gap between cano and brandon phillips... i just wouldn't bet on crawford to reproduce last year's #s... something like .280/12/70/40 would be what i'd expect from carl crawford... anything beyond that would be tits, as the saying goes.
the first/larger trade proposal basically adds on a str8up mauer for mccann aspect, as the 2nd one is the same trade just without the catchers. purely speaking, yeah, i believe mccann is going to give you more homeruns than joe mauer... however, joe mauer is still likely to be the better overall asset when you factor in batting average and runs.
if you're convinced that you've got SBs locked down like a death row inmate and acquiring power is your #1 goal, then i wouldn't make either trade. robbie cano is likely to give you a better BA/HR/RBI clip than brandon phillips at a premium position, and adding in carl crawford and EXPEXCTING ~20HRs isn't the brightest mvoe... however, if you decided you wanted a cadillac in the stolen bases department, then i'd do it. phillips is going to give you lesser stats than cano, but his 15+ steals alongside whatever crawford gives you will help you out there.
for future reference, list your whole team... you gave us a taste of what you have, but like, if you list the whole squad we can give you better advice looking at the big picture as opposed to a little fragment. going with the conditions you defined in your post, i'd say no to these deals because if you're out for purely power you're giving up a superior power-production guy for other guys who are solid, and in tandem yeah it's easy to go "ok 18 homeruns for phillips 18 for crawford that's 36 and cano is a ~25 HR guy so i'm getting more' but keep in mind, this is using two positions to accrue those stats... who's to say you don't get some FA/WW pickup or make a different trade later on? yeah, so purely for power i wouldn't do it.. however, if you decided that your steals game needs an upgrade and you want to get some SBs while trying to technically add a few more HRs, then you maybe consider the first trade... many people are going to mock you and call you retarded for giving up mccann for mauer, however, i believe that mccann has a much much better chance of 20+ HR than does mauer, so if you wanted to make the move for saves and then swap catchers just so you have more HRs, even at the risk of taking an dent in overall fantasy production, then do the first big one. indeed, you do have a desperate owner who is trying to dangle crawford out there so he can upgrade his 2B position by using your desperation... but i'd only do this move if you want/need saves... and depending on the rest of your team, i woudl tender a guess that you likely need more help with steals than you think.
hope this helped... i kind of babble. anyways, here's my super-keeper/franchise leasgue question building for the future.... have a go at it, would ya? viewtopic.php?f=26&t=426473