Broadly speaking you should have a MQL -> SQL -> Deal model (i.e assumptions for ratios between the three) and assumptions for CPL and SQL per SDR/AE.
With these you can tie sales forecasts to marketing spend and sales hires.
Obviously these won't be perfect, but when you're off target you can see why (i.e which assumption was false) and then either try to fix it or correct the false assumption giving you a more accurate model going forward.
Comments
Broadly speaking you should have a MQL -> SQL -> Deal model (i.e assumptions for ratios between the three) and assumptions for CPL and SQL per SDR/AE.
With these you can tie sales forecasts to marketing spend and sales hires.
Obviously these won't be perfect, but when you're off target you can see why (i.e which assumption was false) and then either try to fix it or correct the false assumption giving you a more accurate model going forward.