Sorry to hear that, chardo. Our Duet hasn't shredded anything yet, including items with pre-existing holes.

More information, please:
 What else was included in the load? (no cats, I assume)
 What detergent and additives were used?
 What water temperature?

Did you mistakenly put bleach in the laundry dispenser section? The bleach would basically eat the fibers of the shirt. The bleach has to be put in the correct place on your dispenser. The machine will dispense the bleach for a short period of time before rinsing. With FL and less water the fabric can't be exposed to bleach for very long.

Sorry, but that's about the only reason I could think of why your machine is wrecking your shirt. Of course battery acid (i.e. working on cars) will not show up as holes and tears until after you wash the item.

No bleach or battery acid, no cats (those go in microwave). It was a load of dark shirts and sweatpants. Warm water, Wisk HE detergent, no additives.

Is it possible it got caught in the door somehow?

Perhaps you had something in there with a zipper that wasn't closed. Zippers turn into chain saws when moving arouns in the washer. The MUST be closed prior to washing.

MRB

Zippers? Is that a problem for FL machines? Never bothered with zippers in my old TL and never had any problems. This particular load was t-shirts and sweatpants, some of which had closed zippers at the bottom (they're always closed).

I've never had a problem with zippers with a FL. Did you take a flashlight and look in the drum? Maybe something is caught inside or there is a defect? Check with your hand for smoothness of the surface. Inspect the paddles. (Or whatever you call those things.)

If nothing, then I would give Whirlpool a call.

When I had a FL I found that the high-speed spins caused stress on many older items...tears, holes, etc.

At least I think it was the spin speeds. Anyway, I found I had more clothing damage with the FL than I ever had with my TL.

I started sorting things by fabric weight in addition to colors...and that made even more work. Never again.

I had a cotton thermal blanket stretched/torn in my Neptune TL, and a pair of jeans suffered a perfect 1/2" cut near the crotch.

My neighbor with a Neptune frontloader has had a few shirts develop tears or small holes that could only be attributed to the frontloader. I advised him to make sure zippers are closed on items washed with the shirts. I haven't yet confirmed if that solved the problem from recurring.

Zippers are not problem. I don't close them ever. I wash my white summer pants together w/ lingerie and bras and never had any problems. Bra hooks don't cause problems either. The only problem I had in thirty years using FL ,one of my underwires came out and got hooked in the wash drum hole, pulled out of the bra and got stuck in between the drums. It made snapping noise. I was able to pull it out w/ needle nose pliars. No damage to those drums.
I would check for broken buttons, they can get sharp or the metal gromets on jeans, they get loose or bent sometimes too. Inspect edges of the drum too. You just never know....
I do get tiny holes in cotton t-shirts too but you can tell its from wear and wash, the holes are where the stitches are. Many times the sewing needles damage the apparel when is sewn new and that's where you will see the holes first.

Whirlpool sent someone today to check it out. Looks like the machine was packed too full and the shirt got caught in the gasket around the door. By pulling back the gasket a bit, he found a few pieces of the fabric underneath.

Apparent lesson is not to put too much laundry in the machine. So much for getting more into a front loader.

Do they say you can fit more in a front loader? You must have had that thing really packed.

I think closing zippers is actually a good idea, especially metal ones. Don't always do it though.

We put bras etc into one of those mesh delicates bags.

About packing too much in FL washers. Honestly I agree! The Best wash action in a FL (to me anyway) is when the load in the drum (once saturated) is half way up the door. I'm sure you could get a little more in there where when saturated the load would be 3/4 up the window is a tad bit much for me. I think my Duet can hold a little more laundry than my old 3.2 cu ft TL but not by much. I've washed many loads and been pretty happy with the wash performance, but just watching the wash action when the saturated clothes are more than half way up the door just seems to full to me.

FL can take lots of in and wash it good buy it takes many axtra rinses to properly rinse it out.The lack of water taken in will not rinse the big load in regular cycle. Only comforters are O.K. since they aren't dirty anyway, at least in my case, I use duvet covers.
I posted it somewhere here, I found out if I do only 1/2 to 3/4 size load, it will rinse o.k.. W/ full load I need extra rinses always. I put finished load in my euro washer that spins faster and it was still pulling water and even suds out even thou the big machine wouldn't have suds at all.

The big disadvantage to a FL is that you can't sit on the lid to keep a big (really big) load in it, as two of my dorm-mates did during our freshman year in college. I think they had about a month worth of laundry for the two of them combined in there. Both, of course, are now respectable citizens.