For the past month the Raptors have wallowed. It was as if their every defensive concern came to light, all at a time when Kyle Lowry -- clearly exhausted from fueling the team's offense without DeMar DeRozan -- fell from his early-season immortality. By net rating, the declining Raptors have been one of the 10 worst teams in the league in 2015.

The trend has yet to fully reverse. Toronto will take wins over the Sixers, Pistons, and Pacers, though they offer slim hint of the slump's resolution. Still the Raptors register as one of the more competitive teams in the East by default. None should expect them to fall from the conference's distinct top five, and thanks to their inescapable conquest of the Atlantic division, Toronto will be seeded in the playoffs no lower than fourth. A month of losing basketball, though, does not come without doubts being raised.

Toronto's same, basic core finished the 2013-14 season as a top-10 outfit on both offense and defense. Since the season's turnover, the defense has softened -- a fact that Lowry's creative explosion could only disguise for so long. Once his (and the Raptors') efficiency began to fade, the team's defensive issues shifted from quirk of execution to basis of defeat. One could point to a number of bigger-picture statistical indicators as reason for Toronto's current dip, though for causality's sake it's best to start small with the fact that the Raptors -- athletic as they are -- have the damnedest time staying in front of opponents on the perimeter.

A defense without barriers to entry cannot stand. The initial feedback should make this obvious enough, as allowing Pistons reserve-turned-starter D.J. Augustin 35 points on 20 shots (or Pacers' reserved-turned-starter Rodney Stuckey 22 points on 16 shots) isn't the sign of a particularly healthy system. The fuller view of Toronto's defensive struggles, however, suggests the damage is even more severe. Take this particular sequence from Sunday's game against the Pistons:

Augustin loses Greivis Vasquez completely on this play by stepping to the three-point line with the cadence of a pull-up jumper. When he instead floors the ball, Vasquez is left out of the play entirely and Jonas Valanciunas must assume responsibility for Augustin’s dribble entry. That kind of help is, in itself, essential to systemic defense. Yet by providing it, Valanciunas must leave Andre Drummond from his station just under the rim. Drummond flubs what should be an easy tip-in, though the underlying damage of the initial breakdown is evident.

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​This is just one reason why Toronto’s rebounding deficiencies need be considered in context. Amir Johnson and Patrick Patterson are not the most effective rebounding frontline. Yet their defensive activity -- necessary given how many perimeter players slip through -- also pulls them out of position and forces Toronto's rotating guards to compete with opposing bigs on the glass. One opening begets another.

Breakdowns happen. Even the stingiest teams in the league will make their coaching staff hoarse from yelling. When a team's perimeter defenders allow opponents to get into the lane so consistently, however, it tends to yield high-percentage shots, fouls from late rotations, and offensive rebounds as described above. It is not a coincidence that the Raptors rank in the bottom third of the league by each of these relevant metrics, and in terms of the shot attempts per game surrendered in the restricted area.

To say this needs to be cleaned up is a colossal understatement. Some of Toronto's perimeter players (Vasquez and Lou Williams come to mind) simply aren't intuitive defenders, leading to the surrender of an angle or the buy on a fake. Others (Lowry, DeRozan, Terrence Ross), for a variety of reasons, simply aren't playing up to the caliber of coverage one would expect. There isn't much in the way of a solution save to say that the Raptors will have to do better. These are issues of effort, fundamentals, and lineup alignment that can be addressed -- if not completely fixed -- in time.

Toronto Raptors 2014-15 Scoring Distribution | FindTheBest

Those issues will have to be sorted out if Toronto doesn't have the jolt to score with near-league-leading efficiency as it once did. That endpoint might only be achievable through a crazy proportion of full-tilt Lowry, which with DeRozan back on the floor is not at all practical. For the moment this leaves the Raptors in a strange state: Reliant equally on a worn-down Lowry and an out-of-practice DeRozan as both work their way back to a middle. If one or the other isn't quite right, Toronto is a decidedly less potent team than advertised.

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​This is true in part because the Raptors' top lineups have thus far played to a far lesser advantage than they should. Nearly every team of Toronto's caliber works outward from a starting lineup that mops the floor with its opponents. The starting fives of Washington and Atlanta wreck opponents by double-digit margins per 100 possessions. Cleveland's remodeled starters are thus far outscoring opponents by 15 points. If we look at lineups including Toronto's core four (Lowry, DeRozan, Amir Johnson, and Jonas Valanciunas, given that the other starting spot has been in question lately), in contrast, we find that the Raps' best players edge opponents by a mere 2.4 points.

Depth is an asset for Toronto, but it can only advance the team's play to a point. For now, there isn't a single, proven lineup at Dwane Casey's disposal that consistently dominates the margin against capable opponents. This is why he searches. It's why Valanciunas so often spends crunch time on the bench. It's why Landry Fields played real, NBA minutes this season. It's why James Johnson flew into the rotation and fell out of it. It's why Vasquez is now a starter and Ross a reserve. One can question a particular decision of Casey's, though on the whole his activity is consistent with a coach who doesn't entirely trust the play of his team, and he's right not to.

At some point, though, Casey will need to take a leap of faith regarding some of the Raptors' higher-variance players. There's decent reason in the fans' calls to see more of Johnson, if only in selective situations as matchups allow. Valanciunas -- who hasn't been especially good this season -- also seems desperate for deeper investment, if only because this team could be a standout big man away from a more imposing playoff stature. Neither will provide the Raptors a wide-ranging remedy for all that ails them. Both Johnson and Valanciunas, though, might offer notable advantages in the fuller view of the season if their gradual progress can be tolerated.

This is where the Raptors sit -- their lead in the standings eroded, their confidence surely shaken, and their most evident problems subject to the slow crawl of organic progress. A long regular season allows for the sorting out of just these kinds of challenges, though if the lull continues, Toronto's biggest questions will only intensify.

Statistical support provided by NBA.com.