Let me begin with an unsabermetric rant.  If I ever have to see Luis Castillo in a Mets uniform again, I will break my television in anger.   I hold Luis personally responsible for the collapse in 2007 (remember the let's show bunt on 3-0 craze?) and he wasn't exactly a worldbeater in '08  either.  That the Mets traded a serviceable back up catcher in Drew Butera to get Luis only adds insult to injury.  However, the fact remains that Luis still has one year left on his 4-year $24 million contract that would be Omar's Ishtar, were it not for a certain left-handed pitcher who shall remain nameless.       But the question remains, what should the Mets do at second for 2011 and beyond?  Hope has arrived for some Mets fans in the form of one Tsuyoshi Nishioka.  The 26-year old Nippon League star is being posted by Bobby V's old team, the Chiba Lotte Marines.  As a refresher, when a player is under contract to his Japanese League team, MLB teams are not free to simply sign the player (query whether this violates international trade restrictions).  Instead, the Japanese team "posts" (aka sells) the right to negotiate a contract with the player.  Therefore, the cost for signing a Japanese player must account for both the posting fee to the team and the actual contract reached with the player.  The early returns on Nishioka, who is just 26, are good.  Last year, he hit a robust .346/.423/.482.  He's also a good baserunner who had 22 steals a season earlier.  But, the Mets are going to have to pay a pretty penny for Nishioka.  Figure at least $10-15 mil to the Marines and then a 3-4 year deal worth about $6 mil per season.And here's where I think Sandy et al. are going to say, this isn't worth the risk.  For one thing, Nishioka isn't a sure thing.  His stats translate fairly well to the MLB, but Mets fans know that there's no such thing as a sure thing when it comes to players coming over from Japan.  Further, Nishioka has been injury-prone and 2010 was the first year he stayed healthy for an entire season.  I firmly believe that staying healthy is a skill, and it's one that Nishioka has struggled with in the past.  Finally, and this may be some good news, the Mets actually have options at second--maybe not good ones to begin 2011, but the hope is that the new regime will not just think short term, but long term as well.                      In the short term, the Mets have the makings of a really solid 2B platoon for 2011.  Ruben Tejada against lefties (and coming in as a defensive replacement) and Daniel Murphy against righties.  Interestingly, the Mets have two managerial candidates who can probably speak volumes about the value of a second base platoon:  Wally Backman and Tim Teufel, who complemented each other quite well during the late 1980s.  I know what you're thinking, Tejada can't hit and Murphy can't field.  Well, the latter may be true, we'll have to see.  But, there's good reason to think Tejada just got really unlucky last year:  Tejada's BABIP was a miniscule .250.  And remember, Tejada would only being playing regularly against lefties, and there, albeit in a pretty small sample, he was a totally different hitter, to a tune of (.296/.377/.352).  And of course, Tejada is young,  will likely get better, and is excellent in the field.  Now for the Murph-dog.  Again, we don't know what Murph will do in the field (but he can always be replaced late in games by Tejada).  But we do know, that for his big league career, Murph has hit righties hard.  (.282/.340/.436), and he hit a cool (.301/.391/.455) against them after being called up in 2008.  And there's a third option too:  Justin Turner, who last year at Buffalo hit (.333/.390/.516) with 11 homers.  A Turner/Murphy platoon, while defensively challenged, could really mash at a level comparable to the best we could expect from Nishioka.Oh, and there's the little point about cost.  As noted earlier, Nishioka is likely to cost the Mets at least 15-20 mil next season and probably about $6 mil a year in future seasons.  Murphy and Tejada combined will make less than a million.  Note that going this route doesn't mean the Mets are cheap.  What it means is the Mets understand that they have reasonable internal solutions that can address second base, and they can put the money saved to better use elsewhere.  For example, let's say in 2011 Yu Darvish, the best pitcher in Japan is posted, that $20 mil the mets save by going with Murph/Tejada instead of Nishioka can go a long way towards bringing a true ace to Citi Field.  And we haven't even touched on perhaps the best reason not to make a long-term commitment at Second Base.  The Mets have at least two players in their organization who profile as regulars, and maybe even all-stars at the position.  The oft-injured Reese Havens profiles as a true star, if he can stay healthy (I know, I know,  I said staying healthy was a skill earlier).  Last year, in only 125 at-bats, Havens hit 9 homers and mashed A and AA pitching for a line of (.312/.386/.592).  For a point of comparison, Robbie Cano led all big league second baseman in slugging at .534.  There's perhaps more room to miss with Valdespin, who was merely solid in the minors (.272/.300/.398), but is showing an improved bat, if not improved patience, in the Arizona Fall League at (.355/.388/.461).  If Valdespin can figure out how to take more walks, his production will stabilize, and he can put his speed (7 for 7 in steals in the AFL) to good use.  Note that without improving his patience at the plate, a player like Valdespin, without much power, is going to have wild fluctuations in his performance.  Because a player's batting average on balls in play is subject to so much fluctuation, batting average varies for most players year to year.  Patience, however, is both a virtue and a skill that tends to be a constant.  So, for Valdespin to be a big leaguer, he'll have to figure out how to draw more walks.  But, the good news is, he might do so!And so, the Mets have plenty of options, both for 2011 and beyond.  The worst thing they could do, then, is sign an unknown player to a long-term contract.