Last year, Kennedy was legitimately one of the M's best hitters to start the year. However, since he was just a scrub, over-the-hill bench player pulled off the scrap heap, that was a very bad thing. With Figgins, Jack Cust, Milton Bradley and Jack Wilson as starters, Kennedy and Smoak had to carry the offense at the beginning of the season and there was no way that could last.
This year, if Guillen hits well it will serve to supplement a whole bunch of other quality offensive players instead of being a main driving force. That's a drastically better situation.

All Guillen has to do is revert to the form he showed in '09 and '10 and he's a big help.  He was a 300 AB/100 OPS (roughly) bat for those years.  THAT would be a tremendous help.  That level of performance is certainly not out of the question.
In fact, it is probably to be expected.
Personally, I would ratehr see those 300 ABs go to Liddi (who would be a great lefty/righty platoon partner with Seager) but I think bringing in Guillen probably indicates that isn't going to happen.
And I suppose Guillen's future with the M's is really dependent on Figgins' ST, if we keep him that long.
moe

This is a classic case of how having more information makes us understand a player less. Platoon splits of right-handed hitters are almost always misleading and should be ignored. Even with 2000 PA's against southpaws (which would take over 10 full seasons), you would have to regress a righties observed platoon split by 50%.
Gutierrez has only 700 PA's against lefties so his splits aren't anything to make hay over. If he can hit lefties he can hit righties; they aren't two completely separate skills. If he hits like he is capable of then he will be a very good full-time player.

To make sure Guillen never, ever sees left-handed pitching.  Since 2009
vs. Left:  .228/.291/.331
vs. Right:  .260/.332/.434
Even last year, in an admittedly miniscule sample size;
vs. Left:  .185/.179/.185
vs. Right:  .250/.297/.441
 
It makes him a terrible platoon partner for Seager, I imagine him getting a handful of starts at 3rd, Left, 1st, and probably as many as all those totalled at DH for days when Carp is in Left and Wells is in Center.

Montero at Catcher

Exactly.  Z's trying to put together a team that could win a bunch of games if everything goes right.  300+ Guillen AB's, with 15 doubles and 8 taters would go a long way to helping.
Two main things scare me about the M's offense right now:  #1.  That we get to watch too much of Figgins.  Over the past 4 seasons, Figgins has had 1 horrible one, 2 lousy ones, and one good one.  The good one was driven completely by an outlier # of walks.  That # of walks will never happen again because every pitcher just flat out challenges him.  He can't hurt them so they don't nibble.  #2.  That we get to watch too much of Guti in CF against RHP, whom he flails against terribly. But I suppose I'm beating that point to death.
Used correctly, we have enough bats to score runs.
The Guillen addition doesn't hurt.
moe

Splits are not something to be ignored. In nearly 1800 career PA's, Guti is a .246-.294-.354 vR player.  1800 is a significant sample.  Brendan Ryan, in 1200 career PA's vR, is .252-.303-.341!  1200 PA's is a significant sample.  Like it or not, Guti = Ryan, vRHP. 
Ryan projects to just 12 homers in 1800 PA's vR, while Guti has 30.  But Ryan projects to 80 doubles and 15 triples, while Guti has 71 and 7. 107 extra-base hits for Ryan, 108 for Guti.
1800 PA's is three full seasons of PA's.  It a guy is a .648 OPS player after three full seasons, it suggests he isn't a very good hitter. 
Guti isn't a very good hitter vs. RHP.
Now Wells has only had 178 MLB PA's vs RHP.  That is a quite small sample.  But in it he's a .800+ OPS guy.  As the season starts, Wedge should give him the bulk of the vR starts.  There is the hint that he is a significantly better bat than Guti, in that situation.  We need a significantly better bat.
Splits count.
moe
 

Ghost, I would love to see a Seager/Liddi 3B platoon.
In the 6 seasons where Guti has more than 97 PA's vR, he has never been a league average hitter against righties.  In '07 he OPS'ed (relative to the league vR) 97.  Other than that he has OPS'ed 74, 84, 88, 85 & 54.   Even if you discount last year, he is still well below the league average vR.  He slugged .429 in .07 vR, but other than that he hasn't been above .372....so he doesn't mash the ball either.
On the other hand, he does OPS 130 in relation to the league average against lefties.  He creams lefties.  Against lefties, his OBP is 50 points better and he slugs 100 points better.
He's the perfect definition of a perfect platoon player, if the M's have a capable CF who can hit righties.  I think that is Wells.
If I've done it correctly (which I may not have), based on career numbers, Gti creates 42 runs in 400 AB's vR, and Wells (smaller sample, I know) creates 63.
If correct, that's significant.  Does Guti save 20+ runs over Wells on defense?  I don't know.
I'm suspect we see a bunch of Guti early on (return on investment, I suppose).  I hope he's a bat vR. I'm just not betting much on it.
moe 
 

You can not say that something is a "significant sample" if you don't know what the spread in the population is in regards to that skill. Some stats require a relatively small sample to be meaningful because there is large spread in the measured skill, like groundball-rates. Other stats require a massive sample (almost a whole career) to tease anything out because there is almost no difference between players, like with clutchness. In the case of right-hander platoon splits, it is much closer to the latter. Read The Book to understand what I am talking about, that's where I got the reqression number. For lefty batters the regression is about half that of righties (meaning their is a larger variation among them) and for switch-hitters it's even less, with about 600 PA's needed to regress half-way (which makes sense because they are almost like two different hitters).
The reality is that there is very little variation amongst right-handed hitters (at least as far as major leaguers are concerned) when it comes to their platoon split. So if you see a guy like Guti who has hit lefties extremely well but poorly against righties, then he is almost certainly a better batter against righties than his numbers indicate (and worse against lefties than his numbers suggest). Therefore, platooning him with another right-hander like Wells wouldn't do you any good, especially since Franklin is a better defender.

Because that is what the measured variance of Major League platoon stats suggests.
Long answer:
There are far more right-handed pitchers than lefties, especially at lower levels of the game, like high school and college. This results in the right-handed hitters who reach the Major Leagues having very little difference between them when it comes to platoon splits. There are two reason for this.
First, batters are selected based upon their ability to hit right-handers. If a guy is strong against lefties but weak against righties, his scouting report would not read "Strong against left-handers; weak against right-handers". Instead, his scouting report would just say "Can't hit".
Second, they are forced to face tons of pitchers who have the advantage over them which means by the time they reach the majors they will have maximized their ability to hit those types of pitchers.
Think about penmanship. There is a big difference between how nice some people can write compared to others. There is also a big difference between how most people write with their strong hand compared to their weak hand. Now imagine if everyone were forced to write with their left hand throughout the entire time they were in school. If after their senior year they were then required to take a test measuring their penmanship with both their right hand and left, what would be the result?
For the natural left-handers, you would likely see a wide range of differences between how they write with their right as opposed to left hand because they had so little practice with their weak hand. So a person with very good penmanship could still be really bad with their right hand while person with sloppy hand writing might be just a little worse with their right hand.
But for the natural righties, you wouldn't see as big a range of differences between right and left because they would have so much practice with their weak hand that they were as good as they could be with that weak hand.
We can extend this analogy further. If colleges required students to have good penmanship with their left-hand to be admitted, what would happen? Number one, it would be far easier for natural lefties to get in. Number two,  natural righties would have a small variance between how they write with their left-hand compared to their right hand because the couldn't get in if they struggled with their weak hand.
This is the way it is in the Majors: lefty batters are far more prevalent than they are in the general population and righty batters have very similar actual (as opposed to measured) platoon splits.

 My understanding is...you regress the small split toward the big one a heck of a lot more than you regress the big split to the small.       That must be right. It will be much easier for Guti to raise or lower his vL split because he has less than 40% of the total chances there that he has against righties.
4 years of Guti hitting righties at a .262-.309-.372 clip (his vR line in '09, his break out year) to raise his career avg/OBP/slg 8 pts each!
His career vR #'s aren't going anywhere fast.
moe

Ignore the lefty/righty numbers and just look at his overall stats.

They aren't completely separate skills. If you have two right-handed hitters and both of them are "true" talent .280 batters against right-handers, then you should expect them to hit lefties about equally well regardless of how they had hit lefties in the past.
Or let me put it this way. If you have two righties who both have an .800 OPS over the last 3 years, with one having a very large platoon split, the largest in the game, and the other having no split at all (he had an .800 OPS against both lefties and righties), what should you expect going forward? You should expect them to have essentially the same split going forward. That means it's very possible that the guy who had a huge split could suddenly have almost no split and the guy with no split have a giant split.
Take a look at Edgar Martinez. In most years, he would hit lefties better, sometimes dramatically so, than righties. But in a few years, like in 1998 and 2001, he actually had a reverse platoon split, doing a lot worse against southpaws than righties. That's why we should just focus on a players totals instead of slicing up his numbers into smaller samples that have more noise.

But that means that platooning him with another right-hander like Wells doesn't do you any good. If Wells is a better hitter versus righties than Gutierrez, then he's also a better hitter versus lefties.