Week by week, the Phoenix Suns have suffered blow after blow to their depth. What was once a strongest suit thanks to general manager James Jones’ 3×5 “index card” approach to team-building has become a glaring weakness, due to calculated mistakes over the summer as well as circumstances beyond the Suns’ control.

Starting Cam Johnson over Jae Crowder would’ve zapped the bench of some of its scoring punch anyway, but then Crowder decided he wouldn’t show up to training camp. Eight games into the season, Johnson went down with a torn meniscus, right when he was showing growth in his starting role. In the midst of all this, Cam Payne missed two games with left foot soreness. Ish Wainright has missed most of Phoenix’s games due to lower back pain and then the unfortunate passing of his father.

When word broke that Kevin Durant wanted to be in Phoenix, Jones was right to put all his eggs in that basket. But when he did so and came up holding an empty bag, the Suns missed out on opportunities to put their mid-level exception to use on helpful bench guys. That meant they settled on the margins, attempting to upgrade a short bench with veteran minimum additions and a trade of cash for Jock Landale.

But with Crowder away, Johnson out and Chris Paul leaving Monday’s game due to right heel soreness, the Suns’ already thin rotation is being put to the test. And as much as people want to blame the second unit, it’s two franchise pillars in Deandre Ayton and Mikal Bridges who need to step up most.

Offense sputtering early without Cam Johnson

Granted, we only have two full games to measure since Johnson’s injury, not to mention only 10 games total on the season. But the Suns ranked third in offensive rating before Monday’s ugly loss to the Philadelphia 76ers and have since plummeted to ninth.

“He’s a starter for us, so that’s always a tough blow just to see a guy not be in the lineup, that kind of thing,” coach Monty Williams prophetically said before Saturday’s game. “But that happens throughout the season. You just have to make your adjustments.”

So far, the Suns have struggled to do so. Over the last two games, they’ve scored 102 and 88 points. Their O-rating of 100.5 points per 100 possessions ranks 29th in the league over that span. Phoenix’s 97.8 defensive rating has still been stellar, ranking second in the NBA over those two games, but they’ve felt the absence of Johnson’s floor-spacing, shooting 43.2 percent from the field and 34.7 percent from 3.

Even worse, they’re only taking 24.5 3-point attempts per game over that stretch, which would rank dead-last — by far — in the NBA. Monday’s 6-for-19 performance was the low point for a team that’s averaging 34.1 long-range attempts in wins and 26.7 attempts in defeats.

Even without injuries, there were some uncomfortable adjustments to Phoenix’s strategy of playing Chris Paul off the ball more. The goal of building with more long-term objectives in mind allows Mikal Bridges, Cam Johnson and Landry Shamet to initiate more offense as lead ball-handlers and playmakers. Even if that type of experimentation costs the Suns a win here or there, it could make their playoff offense more versatile no matter the opponent, while also preserving some of CP3’s energy throughout the season.

“Of course you want home-court, but the best feeling is when you’re on a team and you just know that nobody’s gonna be able to beat you four out of seven times,” Paul said over the weekend. “Don’t get it twisted; the regular season is the regular season, and you gotta build, but like I always say, beating a team on a Tuesday night in January, fourth game in five nights…so what?”

That message reverberated up and down the roster throughout training camp.

“I don’t want to say it like this, but it’s two different seasons: There’s the regular season and the playoffs, and we’ve realized that,” Devin Booker said a month ago. “So the regular season is a good time to not only win games but work on those habits and throw in things that we feel that are going to come down later in the line when it matters for us.”

But even with those struggles, the Suns were still a top-three offense and a top-three defense with a healthy Cam Johnson. Without him, now they’re basically missing three starting-caliber players: One injured (Johnson), one who’s nowhere to be found (Crowder), and one in drastically different role who may be banged up now too (Paul).

That puts the onus on Deandre Ayton and Mikal Bridges to pick up their mantles as franchise pillars, and so far, they simply have to be better.

Mikal Bridges needs to take more 3s

Remember that pesky 3-point problem? Well, the Suns can’t continue to fight an uphill battle against math. Three is greater than two, and at the forefront of Phoenix’s 3-point issue is Bridges’ inexplicably low number of attempts.

As a 44 percent 3-point sniper who was taking 7.1 attempts per game, Johnson helped cover up this early-season deficiency. Without him, Bridges’ 2.2 long-range attempts per game is a number that simply has to increase. It’s much lower than his 3.8 attempts per game last season, and it’s half of the 4.4 he was taking on a nightly basis the year before.

In fact, despite playing a career-high 35.9 minutes per game, Bridges is attempting the lowest number of 3s in his NBA career. In 20 fewer minutes per game, Landry Shamet is taking 3.8 3s per game. Cam Payne and Damion Lee are also taking more 3s in significantly fewer minutes. The worst part is Mikal Bridges is a career 37.6 percent shooter from distance who’s made 50 percent of his 3s this year:

He’s been great from the corners, going 5-for-10 from those spots. Unfortunately, generating him 3-point looks a la Cam Johnson hasn’t been a priority for the Suns, since their main focus at this juncture is using him to initiate offense and exploit 4-on-3 mismatches as the roll man in pick-and-rolls.

“That’s something that Golden State has done for years,” Williams explained after the Golden State Warriors game. “It’s just been Draymond [Green] in that, but we feel like Mikal, with his shooting ability, he can stop and pop, he can throw the lob like he did to [Bismack Biyombo], and he can finish.

“I was talking to him about being able to play in that environment, but also being able to make the reads and understand quickly what the defense is doing, and then make a quick play. It’s just another thing that we feel like we can grow that we didn’t have in last year. And that is on me for not taking the risk to do it. Now we’re taking more swings, more bites at the apple, as it relates to giving he and Cam the ball, Landry the ball, and allowing those guys to make plays to try to give us a bit more balance.”

However, with all the emphasis on Bridges growing in a playmaking environment, the scoring and 3-point shooting has taken a hit. On Monday, he finished with 15 points, but he also played 44 minutes, and seven of those points came in the final three minutes, with the outcome all but decided.

Williams was asked about Bridges’ uncharacteristically low number of 3s a few weeks ago and offered up another potential reason.

“I think one thing that’s happened with us, we’ve played a lot of teams who are switching,” Williams said. “And there are times when he’s in the screen, and so he’s diving, so he’s not always at the 3-point line. That may be it. Outside of that, I don’t have a great answer for it, but it is surprising that he doesn’t have more.”

Six games later, little has changed for Bridges, despite facing different types of defenses that don’t all switch. In fact, his 9.5 field goal attempts per 36 minutes are down from 10.8 last year and 10.3 the year prior — all while his 2.7 assists per 36 are only marginal increases from the 2.3 and 2.1 he averaged over the last two seasons.

“I think it’s just any individual that plays basketball, if you kind of have the ball more in your hands, you’re more comfortable,” Bridges said. “Obviously, I know you have Book and C, but just when it does come, it feels good for sure.”

Having the ball in his hands more enhances the playmaking component and even Bridges’ own comfort, but it comes at the cost of his spot-up proficiency. He may be averaging a career-best 14.9 points per game on hyper-efficient .589/.500/.867 shooting splits, but it might be time to trade some of that efficiency for more volume that’ll push him closer to 20 points per game.

Deandre Ayton needs to avoid foul trouble

That goes double for Ayton, who has so often been labeled as the guy who needs to be the second option. With a fully healthy roster, Williams has conceded — even as recently as a few weeks ago — that DA sacrifices touches because of the Suns’ makeup.

“As a scorer, he’s been pretty productive as it is,” Williams said. “He probably would have better numbers or more inflated numbers if he didn’t play with guys who could score as much as Chris and Book and Mikal do. So I don’t think he has to do that. I think there’ll be nights where he’ll have big numbers from a point production, and there’s going to be nights where he’s right at his average. But I think that’s a byproduct of who’s around him, not so much of what he’s not doing.”

However, that quote came before Johnson went down and Paul looked like a shell of himself in a new role. The Suns wanted Ayton to be more aggressive, and even though Booker has continued to cook at career-best levels, now their best movement shooter is hurt and their point guard is taking a backseat.

“I’ve actually told him he needs to be a bit more aggressive, especially around the basket, he tends to pass out a lot ’cause he’s looking for his teammates,” Williams said. “But I don’t think he has to, like, force that issue as far as taking certain shots or expanding his game just so he can have more points.”

Ayton’s lack of creation off the dribble will continue to hold him back until it becomes a fully realized, reliable skill, but the Suns’ offense makes life easy on centers. He doesn’t have to force anything, because perhaps the biggest current obstacle is his sudden bad habit of getting in foul trouble.

DA’s 3.9 fouls per game may not sound like much, but it’s actually been 5.4 fouls per 36 minutes — easily surpassing the 3.0, 3.3, 3.4 and 3.4 fouls he committed per 36 over his first four NBA seasons. That foul trouble has routinely taken him out of the groove and limited him to just 25.8 minutes per game.

From Ayton’s perspective, he’s simply trying to establish himself as a more physical big.

“I’m playing playoff basketball, man,” he said. “I don’t know if it’s the physicality, I don’t know. I’m just trying to play through it and just stick to playing basketball, man. I ain’t letting it get to me too much. I’m not gonna put my level down on the physicality. I’m gonna keep it that way until they adjust to me.”

Considering he’s only averaging 15.3 points per game, it might be time to rethink that approach. It’s far more important to the Suns that he stays on the floor and carries some of the offense than winning some mental battle with the league’s officials to build a reputation as a more physical defender.

Heading into the season, Deandre Ayton stressed his goal was to show “dominance” as a “demonstrative dude” who could take over games. If there were ever a time for him to assert himself and prove he’s ready to be the second fiddle, it’s now. He just has to be on the court long enough to do it.