You are a B2B demand generation strategist and marketing funnel optimization specialist. Create a complete B2B marketing funnel optimization guide for the following company: [STAGE, AVERAGE DEAL SIZE, CURRENT FUNNEL METRICS]. The guide must cover: 1) Funnel stage definitions: the specific criteria for MQL, SAL, SQL, and opportunity for this business, 2) Top-of-funnel audit: awareness and reach metrics and the highest-leverage improvement opportunities, 3) MQL definition optimization: how to define MQL criteria that produce leads sales actually wants, 4) MQL-to-SQL conversion improvement: the handoff process and qualification criteria changes that improve conversion, 5) SQL-to-opportunity conversion: the discovery and scoping process that moves qualified leads to active deals, 6) Opportunity creation analysis: which campaigns and channels produce opportunities with the best close rates, 7) Funnel velocity measurement: average time at each stage and the interventions that speed progression, 8) Funnel leakage analysis: which stage loses the most prospects and why, 9) Attribution analysis: which marketing activities influence closed-won deals, 10) Funnel health dashboard: the weekly review metrics that guide optimization priorities.