Mike Conley's injury is listed as a "right foot strain". It's tough to know exactly what that means but there have been rumblings about plantar fasciitis. That injury is particularly difficult to project or analyze because it's chronic and can range in intensity from "not a big deal" to "oh my goodness I can't even walk". The only real treatment is rest and it gets better or worse depending on how your body responds and how much weight you put on it. Whatever he looks like on Sunday could be the best version or the worst version of Conley we see the entire series.
I had plantar fasciitis one summer. Conley's description, that it's like "walking on a golf ball", certainly matches my experience. The pain is in the middle of your foot and it's present anytime you put weight on it. Mine got so bad I couldn't cut. I would go to plant my foot, the pain would shoot through my leg, and I would involuntarily lift my foot off the ground hobbling around like a wounded dog. Anyone who watched the Bobcats-Heat series from last year (so like 12 other people) saw how debilitating this can be as Al Jefferson struggled to move around the court. Even with painkillers, his mobility was reduced to next to nothing.
For a player like Mike Conley, whose main weapon is his quickness, this could have a major impact on his effectiveness. People often use the term "water bug" to describe smaller guards but I think the term was invented for Conley. He's not necessarily fast, but he can get to top speed in half a step and can go in any direction at any time. He also has the lowest dribble in the league and moves around without leaving his athletic stance. All of this combines to form an image of a crouched guard moving around quickly and in unpredictable spurts.
Conley is famously ambidextrous and has one of the best floaters in the game. His midrange pull up isn't bad either and he's worked to be reliable from behind the arc as well. Like many of Memphis' players, he's dangerous from almost any spot on the floor but never dominant. He may not get all the way to the rim very often but he regularly scoots in and out of the heart of the defense. By getting into the paint, Conley forces the defense to scramble and he opens up all kinds of productive passing lanes.
The effect on the offense is huge. The Grizzlies score 108.4 points per 100 possession with Conley on the floor. That drops to 102.5 when he sits, according to basketball-reference.com. In other words, Memphis scores like the Blazers when he's on the floor and like the Bucks when he's off of it. That's a substantial split and Conley getting into the paint is usually the first step in Memphis' most productive possessions.
The Grizzlies setup Conley for penetration through two main plays. First, like pretty much every team in the NBA, they frequently run high pick and rolls. The Blazers have seen this action thousands of times this year but it's still gives them trouble. Portland drops their bigs farther than most and Damian Lillard and company aren't exactly the best at getting over screens.
Lillard, and most players in general, have an especially difficult time dealing with picks after the ball has been swung from one side to the other. The Grizzlies do a good job of setting up the pick and roll in the above clip. Dame is still moving out of help position as Z-Bo gets ready to hit Lillard with his chest. He hasn't had time to prepare himself for the screen so he runs smack into it.
The above example is purely on Lillard. He just can't get caught going under against a shooter like Conley. However, when Conley penetrates out of these high pick and rolls, the responsibility falls on both defenders. When this happens, Lillard needs to fight through the screen and stay attached to his man's hip. By doing so, he helps bother the ball handler and makes it easier for the big man to contain penetration. This should allow Robin Lopez to step up, cutting off Conley's path before he even touches the paint.
When the Spurs play the Grizzlies, Conley almost never gets below the free throw line. They do a great job ignoring mediocre shooters, packing the lane, and meeting Conley before he can create juicy passing angles or get in range for his floater. This will be the biggest challenge for Lillard if Conley is close to full strength.
Although, side pick and rolls could be a headache as well. The Blazers like to "blue" or "ice" these plays by forcing the ball handler away from the pick. This keeps the ball out of the middle and forces a tough pocket pass to the rolling big man. Even if the offense does get the ball through, there are help defenders in position to bump the roller or slide over and challenge the layup. If the ball handler manages to foil the defense and gets to the middle, well...this happens.
Steve Blake fails to do his job and Conley gets to the middle of the lane. Once he's there, it's very difficult to recover because there are no help defenders to pick up Gasol.
To make this even harder, the Grizzlies use a lot of down screens and dribble handoffs to get Conley curling into the paint. Since Conley gets a running start, Lillard is stuck in a trailing position. That makes it much harder (basically impossible) to keep Conley on the sideline.
These plays are difficult to defend when the player curling has the kind of mid-range touch and passing ability of Mike Conley. The Spurs went under these picks occasionally to cut off the paint without straining their weakside defenders. Lillard does this successfully on this play.
The danger with this is that Conley can abandon the curl and instead flare for a jump shot. If the pick is low enough, that's not a big deal. Conley taking a long two is probably a shot you live with. However, if the pick is a little bit higher, this can get hairy in a hurry.
Conley shot 38% from behind the arc this year. He's always been solid when set but he's really improved on his pull ups and step backs this year. He's now able to burn teams that dare to go under picks. If the screen is anywhere near the three point line, the Blazers needs to trail. This opens up the curl again but, since the pick is higher up the floor, the defense has a few more feet to recover before Conley gets anywhere really dangerous. Getting a sense of where the pick is, staying connected to Conley, and deciding whether to trail or go under the pick is a feel for the game that Lillard just doesn't have. Expect this play to give the Blazers trouble throughout the series.
If Conley lacks the quickness to make these drives, the Grizzlies will be forced to play as if he were on the bench. When this happens, Memphis runs their offense through Marc Gasol and Zach Randolph on the block. Instead of Conley setting up his big men, the big men set up the rest of the roster. Advanced statistics support this observation as Gasol and Randolph both saw the percentage of their field goals that were assisted drop without Conley. This drop was particularly precipitous (15%) for Marc Gasol between 16 feet and the three point line. The Conley-Gasol pick and pop is one of Memphis' bread and butter plays but it isn't nearly as effective with Udrih manning the point.
Beno Udrih has been surprisingly successful in Memphis. His whole game is based around a single skill - his mid-range pull up. Over 50% of Udrih's field goal attempts come between 10 feet and the three point line and he makes over 50% of those shots. That's Chris Paul level efficiency right there. With such a reliable jumper, it makes sense that Beno doesn't attack the paint as often as his counterpart. Since he rarely gets to the rim, Gasol's defender isn't dragged into the paint and Gasol has less space for his 18 foot set shot. Unlike Conley, Udrih's pick and rolls are more likely to end with a shot rather than a pass. This works out alright, but it doesn't lead to the quality looks Conley creates with his penetration.
All in all, the Memphis Grizzlies respond how you would expect a team to respond when they lose their most dynamic offensive player. Each guy on the roster picks up the slack, trying to score more in isolation and playing to their strengths. Even Courtney Lee becomes more active hunting for his own mid-range jumper. They might stay afloat (they sure whooped the Blazers without Conley in January) but all of that effort doesn't change the fact that their offense becomes predictable.
With Conley at full strength and a little bit more shooting, the Grizzlies were finally able to get their offense to a championship level. It's why they were torching the league to start the year and more than a few people were picking them to come out of the West. Without Conley, they're even worse than the team from year's past. Every playoffs they would grind their way through a tough series only to have the points dry up in the end. We'll see how good Conley looks on Sunday and where the Grizzlies fall in between those two extremes. Just remember that depending on the nature of Conley's "foot sprain", we might see multiple different Conleys throughout the series and, by extension, multiple different Grizzlies.
Good luck predicting the outcome of this one.