What mechanisms were at work in Germany at the time of the Schröder-Hartz reforms?

The Schröder-Hartz reforms implemented in Germany after the turn of the century concern ed rules for unemployment benefits and return to employment for job seekers, corporate taxation, organisation of wage negotiations, and the education system. So they had microeconomic components (strong incentives to return to work, decentralisation of wage negotiations, education) as well as macroeconomic components (changes in taxation and wages, and therefore in competitiveness and profitability). When we look at the recovery in the German economy from 2005, what mechanisms can we see at work? Can we explain this recovery merely by macroeconomic developments? It seems that the main mechanism was a reduction in labour costs, which restored service jobs, competitiveness and market shares, profitability and investment.