I enjoy watching Diana Taurasi play, so I was glad that she was on the national TV lineup on Saturday against the Detroit Shock.

Unfortunately, Taurasi had an off night – going 1 for 13 after her 37 point explosion against the Seattle Storm. But what jumped out at me was the Mercury’s rover defense…or rather, how ineffective it was in this loss to the Shock.

The Shock just carved up whatever the Mercury showed them en route to a 89 to 79 victory. Shock rookie forward Tasha Humphrey torched them for 28 points while guard Alexis Hornbuckle pulled down 15 boards. It was that kind of game.

The "rover" is a really interesting defensive scheme because it’s got to be hard for opposing teams to figure out. So I wanted to know more about it…and why more basketball teams don’t use it (although it’s been spreading for years apparently).

So I was left with a bunch of questions that can only be answered by watching more often. But here are a few initial impressions about what went wrong.

What is a Rover Defense?

From what I could tell, the rover is a lot like a match-up zone, though it looks very much like a lax 1-3-1 or 1-2-2 defense. The key is that Taurasi plays the role of "rover" or shadowing a key player that the Mercury wants to shut down. Apparently, Penny Taylor – who chose to stay in Australia to prepare for the Olympics this year – also played the Rover role last year.

There are some good animations of these defenses at The Coach's Clipboard.

Teams play this type of defense in different ways depending on the coach and personnel, but this rover style is typically credited to retired Temple University coaching legend John Chaney.

Where’s the Pressure?

But the key to these defenses – and the first thing I noticed – is putting pressure on the ball. For some reason, Taurasi rarely put any pressure on the lead ball handler. In fact, there was no pressure applied to the offense until they broke the three-point line. That’s a major problem for a zone predicated on movement and quick shifts to keep the offense off balance.

Conventional wisdom holds that the benefit of these types of match-up defenses is putting pressure on the ball and confusing the offense. It’s hard to understand how it would work without that. Without that pressure there are huge holes either along the baseline or in the middle of the key for the offense to exploit for easy baskets (which Detroit did). So although it may have been difficult to identify the type of defense the Mercury were in, Detroit’s perimeter players had no problem finding holes.

Ball movement is the best zone buster

Normally the key to bringing a team out of a zone is to drive the gaps or shoot three pointers to force the defense guard each player straight up. Both of those strategies require good ball movement to over extend the zone and leave someone open.

But without pressure on the ball handlers in a 1-3-1 or 1-2-2 formation, it’s easy to break the zone with quick cuts and good passes between the gaps. That’s exactly what the Shock did.

You have to figure that Bill Laimbeer had this game circled on his calendar after losing the finals to the Mercury and spent extra time with his staff figuring out how to break the Rover defense. Regardless, I thought Detroit perfectly exploited the weak pressure in the zone

Boxing out

Anytime a guard grabs 15 rebounds, it means someone failed to box out. What I saw yesterday with against the Mercury was people running in from outside the paint to grab rebounds over and over again.

Zone rebounding is difficult because there’s no specific defensive assignments to box out as there would be with a "man-to-man" defense. Somehow they’ll have to fix this.

We must be patient with Rover…

There’s more to this story than poor execution and a lot of that is explained by things outside Coach Corey Gaines’ control.

First, Penny Taylor was a major part of this team on both sides of the ball and the Mercury are definitely missing her in the zone defense to help Taurasi out.

Second, Taurasi wasn’t with the team in pre-season, so they weren’t able to integrate the key component of the defense. John Chaney’s Temple teams were notoriously slow starters because it took about half a season to get the defense working properly, even with returning players. Ditto for the Mercury:

"Our rover defense was something we focused on having had Diana and Cappie both here," said . "It was kind of hardhttp://www.blogger.com/img/gl.link.gif to work on it without Diana, who is the rover, and we can’t just throw anybody in that spot. It’s something that took us half a season to get down last year so this week has really helped."

Third, center Tangela Smith is injured right now, so all of the deficiencies a zone presents on the inside are magnified. They haven’t really found an adequate replacement for her.

It’ll be interesting to see how long it takes the Mercury to work this out and turn their season around. It looks like it will require someone to step up and fill the void Penny Taylor has left. I’ll probably come back to this once I watch a few more Mercury games more closely.

Transition Points:

From the Wages of Wins blog: "This year the Shock are again among the top teams in the league while the Mercury - with a record of 2-6 - are struggling. And of course we wonder why the Shock are still on top while the Mercury have declined. The answer - and this will not surprise - is in the stats. But the story will have to wait for another day."

A potential explanation: last year, Penny Taylor was tied with Lauren Jackson for first in the league in "win shares", or the contribution an individual player makes to their teams' overall performance. I’m sure he’ll look more deeply into that. Taylor also led the team in PER.

Relevant Links:

Hustling Shock roll in '07 Finals rematch
http://www.azcentral.com/arizonarepublic/sports/articles/0615mercury0615.html

The Coach's Clipboard
http://www.coachesclipboard.net/MatchUpZone.html

One-On-One With Corey Gaines
http://www.wnba.com/mercury/news/gaines_qa_08050529.html

Chaney Has His Owls In a Zone of Their Own
http://query.nytimes.com/gst/fullpage.html?res=9C03E7D61331F932A15750C0A96F958260