ORIGINAL: Lieste
I'd be happy with a declining fitness (which has greater consequences for the predominantly foot Heer/VGD/FJ units), and lower Aggressiveness, but a less than half value for weapon effectiveness and therefore ability to remain supplied? Seems improbable (IMO), especially given the German propensity to rely on small numbers of infantry (with the LMG) for the bulk of their firepower - it wouldn't be beyond the wit of the unit leaders to ensure that each of these had competent crews, even if the ammunition carriers were as green as grass - again, just IMO.
The poor quality of German units at the end of the war isn't also a purely German problem, the UK and to a lesser extent the US were also scraping the man-power barrel in late 1944-45, with a lot of 'unfit' or LOC troops finding themselves promoted to combat replacements to cope with the shortfall in the supply of manpower.
This is only partially correct. It is true that especially late autumn and winter 44/45 proved to be problematic for the Allies, especially the US, regarding the preparatory training either in the UK or in the actual war Theater, the transport and the deployment of those replacements. The losses, e.g. in the Hürtgenwald (Hürtgen Forest), were unexpectedly high, which almost led to something I would call a "replacement crisis".
Still, compared to quite some German units, which got bootcamp training for 6 (plus X) weeks (less than 2 weeks, sometimes even less than 2 days during the last 3 months of the war), the US units were better off, if you look at how often a soldier would have fired his particular/assigned weapon, and at the level of drill involved.
Quite some divisional US commanders favoured constant drills and training (e.g. specific training to take mountain ranges in Italy, or cliffs in Normandy), but a US study revealed that units, which had received training in the UK (note: after being transfered from US bootcamps) and did without any further training during deployment (in R+R phases) on the European continent, performed as good as units who had constant drill and training scheduled regularly. Again, compare that to the average "Fritz" [;)] with some 2 or 4 weeks of basic training late in the war, then you'll clearly see, that there must have been quality issues, which in fact started to really show in late summer/autumn 1944.
Example as early as August 1944: If you look at the German units involved in the Battle of Falaise, you'll clearly see that there was a "cut", means that the quality deterioriated.
Despite the Allied and German propaganda (Allies: "We destroyed a crack SS unit", Germans: "They defended until the last bullet, inflicting heavy casualties on the enemy ... fought 'til the last man standing"), the majority of the troops of the Hitlerjugend division did not stay, but tried to break through the encirclement. Some sources say 1500 (of 2000 -> after Caen) troops made it back to German lines, most of the remaining inf troops actually pulled out of downtown Failaise at night, leaving the few remaining heavy weapons behind, while its few remaining armored units and other subordinated units had to fight their way eastwards through the bottleneck to the german lines for 3 days. This shows that they did not have the stubborness nor the experience of say a 1942 veteran unit. Understandable, as most of them were kids.
While that division's main cadre (NCOs, COs) consisted of ~1000 veterans from the 1. Panzer-Div LSSAH, the 16,000 troops were drafted directly from the Hitlerjugend. This particular unit, the 12th SS Hitlerjugend was committed ruthlessly in the hinterland area of Juno beach and near Caen, resulting in very high casualty rates, ~3500-4000 dead, 8000 wounded and quite some MIAs, before they retreated south towards Falaise.
These recruits had no experience before Caen, they were partially pretty aggressive, but less effective than units that consisted of older soldiers (above 19 or say 20) and were established in late 1943. It took until March 1944 (5 months) to get this unit ready for deployment, even though the last of the 16,000 recruits was drafted on 1st of September 1943.
Now, if you consider the difficulties and facts described above and the situation (very young recruits, plus reconvalescents and over-age troops, few veterans sprinkled in) of the VGDs, you'll get an idea of what kind of "quality issues" the Germans really had.
The German General (forgot the name) who commanded at least 3 attacks (from different directions) on Bastogne complained and reasoned to his superior - when ordered to take Bastogne after the initial attack failed - that his VGD units were too weak and exhausted to 1) attack again, and 2) that they wouldn't be able to take the objective.
ISTR Dupuy et al, indicating that except in isolated cases, the German "troop quality" remained at 110-120% of the western allies right up until the war's end - the conclusion they reached was this was largely due to small-unit leadership, rather than how good the individual people were.
I do not follow Dupuy there, as the German troop quality varied sometimes from unit to unit, sometimes even from platoon to platoon (e.g. when only some platoons of a company had to be filled with green recruits).
If you consider the numbers of volunteers (17 years old), as well as the number of kids from the Hitler Youth groups, the Reichsarbeitsdienst (RAD), and the "Flak-helper" kids (14-17) that were either pressed into the Wehrmacht or the SS or volunteering for one of these branches, and if you consider the numbers serving in the Volkssturm (the youngest Volkssturm members who fought during the Battle of Berlin were 14 years old) during the final stage of the war, then you'll figure that the amount of "kids" was actually relatively high. These kids were sometimes way smaller than adults, could not carry the same amount of say ammo, weapons, etc., and may not have had the same physical fitness as soldiers who were 20-26 years old.
For the VGD units, (afaik after Himmler and Goebbels intervened) the Germans had upped the upper age limit, they had lowered the minimum requirements regarding fitness, even down to the point where wounded, reconvalescent and lightly handicapped men could be drafted. The fact that the Germans had introduced "stomach"- and "ear"-battalions earlier is quite interesting, and displays how desperate the Germans really were, trying to deploy handicapped soldiers.
My personal feeling is that the poor showing of VGD etc in attack is better represented by poor fatigue recovery, poor reconnaissance and spotting of stationary positions (and a consequent uncoordinated effort) and the ever-present discrepancy between Allied motorised/mechanised forces with many heavy weapons, and the German marching troops, with poor(ish) supply and during dreadful weather.
The most vital parameters were
skill and fatigue.
Skill: In theory, those VGD units, that were equipped with StG44 assault rifles, should have received a vital boost in firepower, resulting in a higher combat effectiveness at close range and medium range, it should have made up for other deficiencies, e.g. the lack of personnel (when understrength) or seasoned grunts, at least.
Quite some authors seem to either forget or not even know about the difficulties when handling these rifles. It took quite some experience to use this weapon effectively, it was not just a matter of days or even a week or two to have its handling down, as this rifle was less forgiving than the MP40 or a grease gun, even though it was pretty accurate up to 400 meters (when firing single shots, if compared to the K98 rifle). While green soldiers had the tendency to grab the MP40 by the magazine and not by its magazine slot, right above the magazine - which often resulted in losing the mag when firing, for example, green soldiers had the tendency to use the StG 44's full auto at medium ranges. Also, the weight and the shaft/slot holding the magazine was anything than ergonomic (for 2nd hand), which was often the reason for less accurate shots.
Mortar fire without a direct/clear FOV, indirect Inf gun fire, these and many other tasks have to be executed by trained and skilled professionals.
The fairly thin scattering of veteran troops would suggest that heavy casualties might reduce combat effectiveness more variably than for a more uniform formation as well... if the casualties are predominantly the raw troops, then combat power may be marginally affected. OTOH, if the relatively scarce veterans are depleted further, then the remaining troops would be very poor indeed.
Well, combat effectiveness was already reduced. I outlined some reasons above.
There were 2 other major showstoppers for combat effectiveness of German units:
1) Leadership:
..... A good example would be the stubborn and unclever attacks with high casualty rates on the Bastogne perimeter, after the encirclement. During at least one major attack the German inf was attacking through the fog in the open, with the last bit (300-600 meters) between the US defenders and the attackers being fog-free (the layer of fog in the background with the silhouettes of the Germans in the foreground then turned this into some target practice for the US paras).
..... Desperate tank attacks carried out without inf support (the unit commander did not even grant time to clear some of the mines) on US held areas in the Hürtgen Forest, where then the German inf had to attack through open terrain after the armored attack failed.
2) War weariness (note: not fatigue):
...... Maybe the most vital factor. Some German veterans had been fighting since 1939, more than 5 years - in December 1944. Others had at least served since 1941 or 1942. This, coupled with physical fatigue, lowered morale and performance. US veterans stated that during the initial phase of the Ardennes offensive German soldiers seemed to be ultra aggressive, with a strange - if not "evil"- glare in their eyes, attacking and killing relentlessly. In fact, there are accounts that German company commanders handed out amphetamin pills, in an attempt to make up for the lack of aggressiveness/drive/morale. I've seen a TV report showing both US and German veteran accounts backing up that detail. They also showed papers handling the order of a huge amount of amphetamins, but it seems that most company commanders (who were approached with this secretely made offer) did either not trust those drugs or did not believe in that kind of "doping".
That said, if COs have to dope their soldiers, it says a lot about the condition of these grunts.