Kotchman's opposite field swing actually makes him a bad fit for the park and the tall grass is terrible for his high GB and slow foot speed IMO. This was one of the debates during the offseason, but I see Kotchman as a poor fit for the park and that might have a little to do with his crazy unlucky BABIP this year.
Kotchman isn't THIS bad, but even adjusting for luck hes been a below RL player and one of the 3 worst players on the roster so far along with Griffey and RRS. Its time to move on.

Z - please go get Kila Kia'ahue (sp?) from KC.  He can't cost that much, never gets a real shot there.  He's been an on-base machine for a long time now and can hit for power.  Yet another season at AAA with OBP north of .400 (actually presently north of .500).  Can't we find a way to give this guy a shot?  If he's got steel hands, let him part DH from the  LH side....sorry Junior...

No doubt that Kotchman has been horrid for the month of May.
No doubt that he should be seeing much less PT.
But, Tui has posted a .316 OPS in five games as a 1B.  (Sweeney and Langerhans are both doing great as 1Bs -- but each has only two games playing 1B).
The reality is that Kotchman was the starting 1B in the 15 run outburst in San Diego.  And Kotchman was also the starting 1B in the (lone) 8-3 victory against the Angels.
Playing Sweeney at first before off days, (extra rest) -- I can see that as a reasonable balance between production and injury concerns.  I'd personally love to see more of Langerhans at 1B, too.  But, Tui has been the worst hitter on the team all season, (even a hair worse than Byrnes).
IMO, the offensive gains more clearly link back to Sweeney - (whether at first or DH), than Kotch. 
As for Kotch's swing.  While I've only gotten to see him in Seattle a few times - here's my take.  Kotch does *NOT* have an "opposite field" swing.  He routinely pulls balls down the line - (from what I read, the DP grounder that ended the most recent game was yanked down the line - leading to a step-on-first-tag-at-second DP.)
What I think is Kotch has a combination of eye and bat control that leaves him in an awkward no man's land too often.  He picks up the ball early - starts his swing and THEN realizes he's getting a change instead of a FB.  While "worse" hitters would swing thru and get a strike - Kotch ends up slowing his bat down to make weak contact on *THOSE* pitches. 
I think the big problem with Kotch is that he begins his swing too early - and then slows it down (on too many pitches).  It's a paradox that his swing "looks" like he's trying to go the other way because he's actually trying to pull the ball - and then is pulling off of too many pitches that his initial read has mis-timed.
So, you get these scorched balls on good 'reads' - and this other subset of 'delayed' reads that turn into weak dribblers on the ground.
I think if you add a 'pause' mechanism to his base swing, to prevent him from getting out in front so often, and you might end up with a decent 110 OPS+ hitter.  Instead, it feels like he's getting the exact wrong advice for HIS problem -- and the result is a Sexson-esque disaster.
There's no doubt his eye is stellar.
There is no doubt he can put wood on the ball about as well as Vlad. 
In the end, whatever tweaks the club/Kotch have tried - they clearly have had dreadful results.  You'd think someone with THAT good an eye - *PLUS* - that much bat control could learn how to put the two together for at least a reasonable average (power or not). 
I get the sense of the novice bowler who is missing right, so he keeps moving left, and the problem gets worse.  What he doesn't get is, if you're missing right, you MOVE right. 
This is not to say he belongs in the lineup.  I'm one of Carp's biggest fans, and if Kotch stinking it up can get Carp up a month or two sooner, I'm okay with that. 
Then again, Lopez stunk it up just as badly for just as long - and in the last week has suddenly put it all together and looks like "Good Jose" again.  I'd be pleased as punch to see Langerhans playing first - Sweeney DHing - and Bradley in LF as much as possible. 
Unfortunately, even with the offense coming around, the bullpen is a mess, and I fear won't be getting much better.
Here are the HR/9 rates of the top three guys:
Aardsma: 1.7; League 1.3; Kelley 1.4;
If that's your CREAM - you can expect to be losing more games to bullpen dingers.

His May has been horrid, not many line drives, all the ground balls he wasn't hitting in April, but...there are a few extenuating circumstances.  I read fairly early in the month that he was getting a day off because he was "banged up", maybe it's a euphamism for hitting lousy, but if he was hurt, then he was hurt.  Also, the numbers have been unlucky, about 2 weeks ago he hit a ball and posed, stupid, and he turned a double into a single that got him thrown out at second, in the game where Griffey hit his game winning single, Casey missed a towering homerun by a few feet, and then walked, last night, his game losing double play was described as a shot down the line that Morneau snagged in a great play.  He's still only batting .500 on his line drives.
Going back to the possibility that he's playing hurt, there is some evidence to support that theory.  Casey Kotchman hasn't been played much lately, but 3 of his last 4 starts?  Against left handers...if Wak was going to stop using him, wouldn't he start him against righties when he started him?  What sense does it make to take a guy who's a little above average against righties, and awful against lefties, and start him almost exclusively against lefties, unless he's trying to turn fans against him.

"I get the sense of the novice bowler who is missing right, so he keeps moving left, and the problem gets worse.  What he doesn't get is, if you're missing right, you MOVE right."
 
Love the bowlling reference Sandy (coming from a former PBA member).  I've seen great bowlers get coached backward in that sense too.  The coaches bring their ideas of how a game SHOULD be played into the context too.  I had a local bowling coach who did exactly as you say.  But the problem is, he did all of his coaching in house where the shot was SO forgiving that the more you banked it, the more it seemed to work out.  On the other hand, I got some coaching from John Jowdy on tour who wanted everyone to fit into his loose armswing (to the extreme) method - a method that worked much better for my style. 
The problem with any of these approaches is that the coaching contexts may be also having an affect.  Back to the baseball context with Kotch, how would a coach 1) be able to discern the decelerating bat, and 2) be able to use some sort of cue to correct it? 
You can't just say, "hey Casey, keep that bat-speed all the way through your stroke".  Without a meaningful cue, a lifetime of muscle memory is going to be extremely difficult to change.  And if they are trying to change it, we would probably see exactly what we are seeing. 
Anyway, always appreciate a bowling reference Sandy.  Keep 'em coming.

Wow - a PBAer.  Who'd a-thunk it?
Just fyi - back in the day, my right-hand average peaked at 174.  I blew out my knee playing basketball and switched to lefty.  I peaked with a 144 as a southpaw.  (I had a monster, natural hook as a lefty - and never did learn to control it -- while as a righty, it was all I could do to generate the softest of baby hooks - even with a top-weighted, fingertip ball.  Go figure).
My suggestion for Casey was to add a timing mechanism to this "wind-up".  If he starts the bat later, he'll have no choice but to be accellerating through the ball.  But, I'm even less of a batting coach than I am a bowling coach.  So, probably best to leave it all in the hypothetical arena.

Would love some Kila.
Its too late to buy low on Seth Smith (my favorite hitting sleeper last offseason), but Kila seems to be up for grabs. Hes not MLB proven yet, but his upside certainly exceeds his current stock with KC.
What a great target that is for this organization.

Carp was struggling pretty bad earlier in the year, but in his last 10 games his slash line is: .371/.425/.743/1.168 w/ a double and 3 HRs and his eye rounding back in to the just under 1:1 status that he had previously.  I would think now is the time, especially with Griffey's spot on the bench opening up, to bring up a hot Carp and give him a couple of weeks at first to see what he can do.
Bring up the Fish!