Saved by the Bell, are we lacking defensively?

I am writing this the morning after Luton Town crashed out the FA Cup following a 3-0 loss to Grimsby Town in the Fourth Round replay. It was an unfortunate loss, of which there are several factors to consider. We rotated the majority of our midfield, with only Allan Campbell retaining his place from the victory over Stoke. Otherwise it was a case of Elliot Thorpe playing an unfamiliar wing back position, due to the resting of Doughty and ineligibility of Drameh. Up front Elijah Adebayo had to play a full 90, with Woodrow swapping in for Morris, again due to the ineligibility of new signing Joe Taylor and recalled Muskwe. At the back the only change was Gabe Osho in for Reece Burke. For two of the Grimsby goals, the ease at which they played into our box, was concerning. However, enough negativity, we take this result on the chin and focus on the league now. Due to the fresh absence of Dan Potts, enforced by injury and the continued absence of Sonny Bradley, who is now back out on the grass, fortunately. Our defensive options now include 4 players for the 3 positions, these being Tom Lockyer, Reece Burke, Gabe Osho and Amari'i Bell. Although Rob Edwards and programme notes from the Town CEO Gary Sweet and Chairman David Wilkinson have both stated that supporter criticism of the clubs transfer policy is misplaced, as the club work within a budget and we have exited the transfer window in a stronger position than we entered. The overhanging concern remains that with a hectic schedule approaching, the 4 available options look like they are going to required to play 9 matches before the next international break in 38 days, a game every 4 days. The statements that we entered the transfer window stronger than we left is slightly flimsy, Drameh does appear to be a more attacking replacement for James Bree, Marvelous Nakamba is a sublime capture. However, Jerome and Cornick are two rotation options, although this provides a superb development opportunity for Muskwe and Taylor. A common argument is that defensively, we have not exited the window in a stronger position. Yes, we can point to the back to back to back clean sheets, although these were against Wigan, Cardiff and Stoke, three teams who are struggling going forward this season. We can also point to that we have only conceded 29 goals this season (1.0 per match) which is 4th best in the league, this is supported by our ability to win the ball back in the final third, with Luton also 4th in the league for high turnovers (4.6 per match, a total of 688). We can also point to Luton Town exhibiting the 4th lowest xG conceded (quality of chances against us) in the league (28.6 - for reference Burnley is 28.5, Middlesbrough 28.2 and Sheffield United 28.0). We can also point at our clean sheet record being the second highest in the League (12). All this without signing a central defender? How is this happening? A big clue to our defensive quality was stated by Rob Edwards in his post Stoke press conference, we work as a unit, defending starts from the front. A big part of our quality certainly comes from our high press, and high work rate through the team. However, we also have exceptional defenders currently playing in our back 3, who are on average the 4th best defence in the Championship. I would have picked out Lockyer to discuss, but he has been a brick wall all season. I am picking out Amari'i Bell as the recent standout in the back 3. In the absence of Dan Potts, Amari'i has shown exceptional one on one defending and great attacking underlaps in the central areas, however, it's not easy playing out of position and full credit goes to Amari'i being another to step into the back 3 in lieu of specialist centre backs. He's done what's required of him, winning all his tackles, making 20 recoveries and 13 clearances while playing at the back. We may be light on the ground defensively, however we defend as a whole team. Although this may be concerning for fans our defensive statistics are most certainly hiding our lack of depth in the back 3 positions. If Amari'i Bell got injured, we have simply run out of squad players that we can shoehorn into that backline, which is certainly a concern, although we could probably stick Simon Parsell next to Tom Lockyer and absolutely fine. To conclude, we may be struggling with defensive options, but defensively we are not struggling with our performances only being outdone by Sheffield United, Burnley and Middlesbrough, which is good company be in!