By now the Spanish government likely knows how it fared in 2011. And it probably knew by the end of December, when it announced that the national deficit would be just above 8% of the GDP.
Rajoy was not just pulling numbers out of his hat, but, like other EU leaders, based his comments on a provisional estimations provided by the Intervención del Estado. Therefore, it is hard to see how the EU could not be suspicious about the fact that Spain has not supplied any data yet.
They will not provide the data until April 3. How can the EU sanction one of its member states based on mere conjecture?